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Article

You Are What You Eat: California Sea Cucumbers Become “Fishier” After Integrated Multi-Trophic Aquaculture with Chinook Salmon

by
Emaline M. Montgomery
1,
Barb L. Cannon
2,
Miki Nomura
3,
Rodrigo B. Leme
2,
Ian P. Forster
3 and
Christopher M. Pearce
1,*
1
Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, BC V9T 6N7, Canada
2
Creative Salmon Co., Ltd., Tofino, BC V0R 2Z0, Canada
3
Fisheries and Oceans Canada, Pacific Science Enterprise Centre, West Vancouver, BC V7V 1H2, Canada
*
Author to whom correspondence should be addressed.
Fishes 2025, 10(4), 154; https://doi.org/10.3390/fishes10040154
Submission received: 17 December 2024 / Revised: 12 March 2025 / Accepted: 16 March 2025 / Published: 1 April 2025
(This article belongs to the Special Issue Advances in Integrated Multi-Trophic Aquaculture)
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Abstract

:
Recent interest in integrated multi-trophic aquaculture (IMTA) as an ecologically-sustainable and climate-conscious aquaculture system has resulted in testing different species partnerships and configurations in anticipation of industrialization. Deposit feeders like the California sea cucumber (Apostichopus californicus) have been suggested as ideal partners for IMTA with finfish, due to their ability to consume fish waste as well as their passive nature. However, the nutritional impacts of feeding on fish waste in IMTA have not yet been established for this species. The present study tested the effect of 3 months of inclusion in IMTA with Chinook salmon (Oncorhynchus tshawytscha) on the fatty-acid and nitrogenous-metabolite profiles of California sea cucumbers. The fatty-acid profiles of IMTA sea cucumbers showed significant changes from wild reference individuals, while few differences were detected in amino acids and other nitrogenous metabolites. Sea cucumbers housed directly in cages with salmon showed distinct shifts in their fatty-acid profiles toward higher levels of MUFAs and lower levels of SFAs, while PUFA concentrations remained the same. Sea cucumbers included in IMTA with finfish may be even more healthful for humans due to the accumulation of certain unsaturated fatty acids in their tissues not seen in wild reference individuals.
Keywords:
amino acids; Apostichopus californicus; Chinook salmon; fatty acids; IMTA; integrated multi-trophic aquaculture; metabolites; sea cucumber
Key Contribution: Fatty-acid profiles of IMTA sea cucumbers showed significant changes from wild reference individuals, while few differences were detected in amino acids and other nitrogenous metabolites.

1. Introduction

Research interest in integrated multi-trophic aquaculture (IMTA) has intensified around the world due to the purported benefits of this aquaculture system, including improved ecological sustainability, increased productivity, species diversification, and climate-change mitigation [1,2,3,4,5]. IMTA attempts to mimic natural partnerships among species, with some producing wastes—including feces, pseudofeces, and uneaten feed—and others consuming that waste, termed primary and extractive species, respectively [5]. Common examples of waste-producing species are finfish [6,7], crustaceans [8], and other fed/unfed invertebrates [9], while examples of extractive species are unfed invertebrates (e.g., oysters, mussels, sea urchins, and sea cucumbers) and macroalgae [10,11,12].
Deposit-feeding sea cucumbers have long been considered ideal partners for IMTA due to their ability to consume, assimilate, and transform inorganic nitrogen and phosphorus compounds found in fish feces, shellfish feces/pseudofeces, and uneaten commercial feed pellets/fines [13,14,15,16]. They are also behaviorally passive and do not contain potentially damaging appendages (cf. sea urchins with spines), meaning they can potentially be housed safely with other species. So far, the majority of research on sea cucumber IMTA has been conducted in China with the Japanese sea cucumber (Apostichopus japonicus; for a review see [17]), although some work has explored IMTA with other species such as Holothuria forskali [18], Holothuria poli [7,19], Holothuria scabra [6], and Holothuria tubulosa [20,21]. Two commercial sea cucumber species from Canada have also been assessed for their IMTA potential: the orange-footed sea cucumber (Cucumaria frondosa) in the Atlantic Ocean [22,23] and the California sea cucumber (A. californicus) in the Pacific Ocean [13,14], [24,25,26]; and see review [27].
Biochemical changes in sea cucumbers as a result of inclusion in IMTA have been explored in A. japonicus, including stable isotopes [28] and fatty acids [29]. Those studies confirmed that deposit-feeding sea cucumbers feed on fish wastes when cultured in IMTA with fish and that biochemical changes in the sea cucumber tissues can be detected after only a few weeks. Given the importance of fatty acids and amino acids to taste and tissue quality [30,31,32], understanding the biochemical changes experienced by sea cucumbers in IMTA is a key part of developing standard operating procedures (SOPs) for the industry, including optimizing placement on the farm, length of exposure, and diet. Shifts in stable isotopes have been reported for California sea cucumbers grown in finfish IMTA [25], but few studies have explored fatty acids or nitrogenous metabolites in this species either in the wild or in aquaculture systems [27]. This is surprising, given the economic importance of the well-established California sea cucumber dive fishery along the west coast of North America [33,34] and the budding aquaculture industry for this species in Canada and the USA [27].
To address this gap, we explored the fatty-acid and nitrogenous-metabolite profiles of California sea cucumbers included in IMTA with Chinook salmon (Oncorhynchus tshawytscha) for 3 months. The study had two main objectives: (1) to assess the profile differences between sea cucumbers housed on finfish sites for 3 months and wild reference sea cucumbers and (2) to assess the effect of proximity to the fish on the biochemical profiles of IMTA sea cucumbers held directly in cages with fish or in neighboring empty cages (direct versus indirect IMTA). This is the first study to test the effect of finfish IMTA on the biochemical composition of California sea cucumber tissues. The findings will be useful for the development of an IMTA framework for aquaculture of this species in the northeast Pacific Ocean as well as for improving knowledge of nutritional patterns of deposit-feeding sea cucumbers.

2. Materials and Methods

2.1. Study Area, Farm Parameters, and Source of Sea Cucumbers

The study was conducted at two commercial Chinook salmon (Oncorhynchus tshawytscha) farm sites in Clayoquot Sound, British Columbia (BC), Canada, owned and operated by Creative Salmon Co., Ltd. in summer 2021 (Figure 1). One site was located in Dawley Pass (DP; 49° 09′ 56.3″ N, 125° 46′ 10.7″ W) and the other was situated near Warne Island (WI; 49° 07′ 41.6″ N, 125° 44′ 58.6″ W). Both farm sites used for the study had mature Chinook salmon broodstock housed within designated net cages (15 × 15 × 15 m Viking-style cages with 4 cm stretch nylon netting). Fish density was according to normal industry practice and stock availability, with densities in the 3−4 kg m−3 range. Fish were fed daily to satiation, using underwater cameras to ensure adequate amounts of food were made available. Two brands of feed were used at both sites: Taplow Ventures Ltd. (Vancouver, BC, Canada) and EWOS/Cargill Aqua Nutrition (Bathgate, UK), based on the practices of our industry partner. Four hundred wild California sea cucumbers (>15 cm contracted length, measured after 5 s of consistent handling in air) were hand collected by SCUBA in Clayoquot Sound at a distance >1 km from the farm sites for use in the study (Figure 1).

2.2. Experimental Design and Tissue Sampling

Two experimental treatments were established to test the effect of inclusion in Chinook salmon IMTA on the fatty-acid and nitrogenous-metabolite profiles of sea cucumber tissues: (1) 100 sea cucumbers with fish (F + S) and (2) 100 sea cucumbers without fish (S). Stocking density of the sea cucumbers was 1 individual per ~11 m2 of net surface area, which was chosen based on the research of [35]. Both treatments were established in cages at both farm sites, and the experiment was conducted from July to September 2021 (3 months). Sea cucumbers in the F + S cages actively fed on excess food and salmon feces, while those in the S cages fed on biofouling material that collected on the walls of the cages [25]. All nets were cleaned at the end of each month via power washing and sun drying using industry practices. Prior to the net cleaning, all sea cucumbers were transferred by divers to floating cages in the center of each fish pen in order to prevent damage or stress, as per [25].
Three haphazardly-chosen sea cucumbers from each replicate cage of both experimental treatments at both farm sites were collected after 1, 2, or 3 months of inclusion in IMTA (i.e., n = 6 per treatment per sampling month, combining across sites (see Section 2.3, Statistical Analysis)) for fatty-acid and nitrogenous-metabolite sampling (see below). Additionally, six wild sea cucumbers were collected at the end of the experiment from a reference site (R) > 1 km away from the two farms to compare with farmed sea cucumbers after 3 months of IMTA. Wild samples were compared only with farmed samples that had been exposed to IMTA for 3 months, as seasonal differences in fatty-acid profiles among wild individuals were expected. The body walls and muscle bands of all sampled sea cucumbers were separated during dissection and were analyzed separately.

2.2.1. Fatty Acids

Tissue samples were freeze-dried and ground and then esterified, the resulting fatty- acid methyl esters (FAMEs) being extracted following the method of Puttick et al. (2009) [36]. Approximately 200 mg of each sample was placed in a glass screw-cap tube with 2 mL of 3 M HCl in methanol and 0.5 mL of an internal standard (1 mg ml−1 of C19:0 in hexane). Each tube was capped tightly with Teflon tape and then incubated for 16 h at 80 °C. After cooling, 2.0 mL of 0.3% saline solution was added gradually, followed by 1.5 mL of hexane. Each tube was shaken vigorously, then centrifuged at 2500 rpm for 5 min. The resulting supernatant containing the FAMEs was transferred to 2 mL glass vials for analysis by gas chromatography on a Scion 436 gas chromatograph fitted with an Agilent DB-23 column. Fatty-acid profiles were quantified by relative %, a total of 31 fatty acids being detected at levels >0.5%, including a variety of saturated (SFAs), monounsaturated (MUFAs), and polyunsaturated (PUFAs) fatty acids. Fatty-acid profiles were also determined for the two types of dry commercial fish pellets used at both farm sites to feed the Chinook broodstock. This work was completed by the Nutrition Laboratory at the Pacific Science Enterprise Centre (Fisheries and Oceans Canada) in Vancouver, BC.

2.2.2. Nitrogenous Metabolites

Nitrogenous metabolites were quantified by relative % using ultra-performance liquid chromatography–electrospray ionization–tandem mass spectrometry in multiple reactions monitoring mode (UPLC-MRM-MS). A total of 165 metabolites were quantified including amines (AMs), essential amino acids (EAAs), non-essential amino acids (NEAAs), non-proteinogenic amino acids (NPAAs), and organoheterocyclics (OHCs). This work was completed by the Genome British Columbia Proteomics Centre at the University of Victoria in Victoria, BC.

2.3. Statistical Analysis

All statistical analyses were conducted using R statistical software [37], and graphics were produced using the ggplot2 package [38]. Significance was set at α = 0.05 for all tests. We first assessed the potential effect of farm site on fatty-acid and metabolite relative % composition for sea cucumber muscle bands and body walls using Kruskal–Wallis tests, since data normalities were violated and could not be rectified by various data transformations. Since no significant site effects were detected in either analysis, values from both farm sites were pooled for subsequent analyses using multiple two-way aligned ranks transformation ANOVAs [39,40], since assumptions of normality could not be met, even after trying various data transformations. Non-parametric, post hoc, multiple comparisons tests were conducted when interactions between the tested factors were significant. We first examined the effects of sea cucumber type (wild versus farmed (F + S and S combined)) and tissue type (body wall versus muscle) on fatty-acid and nitrogenous-metabolite profiles after 3 months of IMTA. We then looked at the effects of IMTA duration (1, 2, 3 months) and proximity to the fish (F + S, S) for each tissue type separately. Finally, complete fatty-acid and nitrogenous-metabolite profiles were analyzed using principal component analysis (PCA) with unsupervised hierarchical clustering on principal components (HCPC; [41,42]). Fatty acids and metabolites were included in the analysis if they were >0.5% of the total composition for the sample.

3. Results

3.1. Fatty Acids

3.1.1. Effects of Sea Cucumber Treatment (Wild Versus Farmed) and Tissue Type (Body Wall Versus Muscle Band) After 3 Months of IMTA

The relative composition (%) of three categories of lipids (SFAs, MUFAs, PUFAs) differed among the sea cucumber tissue types and treatments. SFAs were significantly affected by sea cucumber treatment (F1,26 = 22.8, p < 0.01) and tissue type (F1,26 = 28.1, p < 0.01), but not by the interaction between them (F1,26 = 0.9, p = 0.35). Farmed sea cucumbers had significantly lower levels of SFAs than their wild counterparts, while the muscle bands had significantly lower levels than the body walls (Figure 2A). MUFAs were significantly affected by sea cucumber treatment (F1,26 = 24.1, p < 0.01), tissue type (F1,26 = 11.9, p < 0.01), and their interaction (F1,26 = 6.0, p = 0.02). Post hoc multiple comparisons showed the general trend that farmed sea cucumbers had significantly higher levels of MUFAs than their wild counterparts, while muscle bands had significantly lower levels of MUFAs than body walls (Figure 2B). PUFAs were significantly affected by tissue type (F1,26 = 46.6, p < 0.01) and the interaction with sea cucumber treatment (F1,26 = 17.8, p < 0.01), but not by sea cucumber treatment (F1,26 = 0.002, p = 0.96). Post hoc multiple comparisons revealed that the muscle bands had significantly higher levels of PUFAs than the body walls, but that farmed versus wild did not differ significantly within the tissue types (Figure 2C).
Eicosenoic acid (20:1n-11) was a unique MUFA found only in farmed sea cucumber tissues (Supplemental Table S1). Regarding PUFAs, relatively higher (~5% higher) levels of n-3s, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were found in farmed than in wild individuals (Supplemental Table S1). Docosapentaenoic acid (22:5n-6) was a unique PUFA found only in farmed sea cucumber tissues. Other n-6 fatty acids like adrenic acid (22:4n-6) were depleted in the farmed sea cucumbers compared with wild individuals (Supplemental Table S1). The most common fatty acids in farmed sea cucumber body walls were palmitic acid (16:0; 16.6 ± 2.3% of body-wall fatty acids. mean ± SD), palmitoleic acid (16:1n-7; 12.9 ± 3.7%), DHA (22:6n-3; 11.0 ± 2.8%), and EPA (20:5n-3; 9.8 ± 2.3%), while EPA (20:5n-3; 14.9 ± 2.3%), DHA (22:6n-3; 11.3 ± 2.4%), arachidonic acid (20:4n-6; 10.2 ± 1.7%), and palmitic acid (16:0; 9.9 ± 2.1%) were the most common fatty acids in farmed sea cucumber muscle bands (Supplemental Table S1). At the end of the experiment, the mean ± SE levels of total fatty acids, EPA, and DHA in the body walls of the experimental sea cucumbers were 4.75 ± 0.22, 0.42 ± 0.02, and 0.45 ± 0.04 g/100 g dry tissue, respectively. Those for the muscle bands of experimental sea cucumbers were 2.54 ± 0.08, 0.34 ± 0.01, and 0.25 ± 0.01 g/100 g dry tissue, respectively. Likewise, those for the body walls of reference individuals were 5.91 ± 0.41, 0.48 ± 0.04, and 0.38 ± 0.03 g/100 g dry tissue and for the muscle bands were 2.55 ± 0.05, 0.32 ± 0.01, and 0.18 ± 0.01 g/100 g dry tissue, respectively. SFAs and MUFAs were less common in muscle bands than in body walls, but the reverse was true for PUFAs (Figure 2).

3.1.2. Effects of Sea Cucumber Proximity to Fish During IMTA (F + S Versus S) and Length of IMTA (1, 2, or 3 Months)

The relative composition (%) of three categories of lipids (SFAs, MUFAs, PUFAs) also differed among sea cucumber tissue types and the proximity to fish while in IMTA. SFAs in sea cucumber body walls were significantly affected by fish proximity (F1,30 = 5.3, p = 0.03) and the interaction with IMTA duration (F2,30 = 3.9, p = 0.03) but not by IMTA duration (F2,30 = 0.9, p = 0.41). Post hoc multiple comparisons showed that F + S sea cucumbers had significantly lower levels of SFAs than S sea cucumbers after 3 months but revealed no other significant differences between the two treatments before that time point (Figure 3A). MUFAs in sea cucumber body walls were also significantly affected by fish proximity (F1,30 = 5.8, p = 0.02) and the interaction with IMTA duration (F2,30 = 6.7, p < 0.01) but not by IMTA duration (F2,30 = 0.4, p = 0.65). Post hoc multiple comparisons showed that F + S sea cucumbers had significantly higher levels of MUFAs than S sea cucumbers after 3 months of IMTA, but they revealed no other significant differences between the two treatments before that time point (Figure 3B). PUFAs in sea cucumber body walls were not significantly affected by fish proximity, duration of IMTA, or the interaction of the two factors (Figure 3C). SFAs, MUFAs, and PUFAs in sea cucumber muscle bands were also not significantly affected by fish proximity, duration of IMTA, or their interaction (Figure 3A–C).

3.1.3. Unsupervised Hierarchical Clustering Analysis

Unsupervised hierarchical clustering (HCPC) analysis of 31 individual fatty acids in the two sea cucumber tissue types revealed seven clusters based on tissue type, proximity to the fish (for sea cucumbers included in IMTA), and wild versus farmed: (1) F + S muscle bands, (2) S muscle bands, (3) F + S body walls, (4) S body walls, (5) wild muscle bands, (6) wild body walls, and (7) commercial salmon food (included as a reference point) (Figure 4, Table 1). Sea cucumbers included in IMTA (F + S and S, clusters 1−4) were enriched with 9-eicosenoic acid (20:1n-9), nervonic acid (24:1n-9), 3-docosapentaenoic acid (22:5n-3), 6-docosapentaenoic acid (22:5n-6), and DHA (22:6n-3), while wild sea cucumbers (clusters 6−7) were enriched with unique SFAs like arachidic acid (20:0), henicosanoic acid (21:0), and behenic acid (22:0) (Table 1; HCPC p < 0.01). The commercial salmon food (cluster 5) was enriched in five fatty acids, seen only at trace levels (<1%) in the sea cucumber tissue samples: myristic acid (14:0), margaric acid (17:1), asclepic acid (18:1n-7), α-linolenic acid (18:3n-3), and stearidonic acid (18:4n-3) (Table 1; p < 0.01).

3.2. Nitrogenous Metabolites

3.2.1. Effects of Sea Cucumber Treatment (Wild Versus Farmed) and Tissue Type (Body Wall Versus Muscle Band) After 3 Months of IMTA

The relative composition (%) of four categories of nitrogenous metabolites (AMs, EAAs, NPAAs, OHCs) differed significantly among the sea cucumber tissue types, while one category (NEAAs) differed significantly between the experimental treatments. AMs, EAAs, NPAAs, and OHCs were all significantly affected by sea cucumber tissue type (F1,10 = 31.4, p < 0.01; F1,10 = 32.7, p < 0.01; F1,10 = 32.0, p < 0.01; F1,10 = 34.3, p < 0.01, respectively), but not by sea cucumber treatment (F1,10 = 0.1, p = 0.73; F1,10 = 2.8, p = 0.12; F1,10 = 1.3, p = 0.29; F1,10 = 1.5, p = 0.25, respectively) or the interaction between them (F1,10 = 0.3, p = 0.61; F1,10 = 1.3, p = 0.28; F1,10 = 0.0003, p = 0.99; F1,10 = 1.7, p = 0.22, respectively). Body walls had significantly higher levels of AMs, EAAs, and OHCs than muscle bands, but the reverse was true for NPAAs (Figure 5A,B,D,E). NEAAs, however, were significantly affected by sea cucumber treatment (F1,10 = 7.4, p = 0.02), but not by sea cucumber tissue type (F1,10 = 0.3, p = 0.58) or the interaction between them (F1,10 = 0.2, p = 0.67). Farmed sea cucumbers had significantly higher levels than wild individuals (Figure 5C).
The most common amino acids found in farmed sea cucumber body walls were leucine (15.6 ± 1.4% of body wall proteinogenic amino acids, mean ± SD), phenylalanine (13.5 ± 1.6%), glutamic acid (13.1 ± 3.9%), and alanine (10.7 ± 4.5%), while arginine (25.4 ± 4.9% of muscle band proteinogenic amino acids, mean ± SD), proline (23.2 ± 2.2%), alanine (19.0 ± 6.4%), and glutamic acid (9.5 ± 2.0%) were the most common amino acids in farmed sea cucumber muscle bands (Supplemental Table S2).

3.2.2. Effects of Sea Cucumber Proximity to Fish During IMTA (F + S Versus S) and Length of IMTA (1, 2, or 3 Months)

NEAAs in sea cucumber body walls were significantly affected by the duration of IMTA (F2,14 = 5.1, p = 0.02) and the interaction with fish proximity (F2,14 = 5.0, p = 0.02) but not by fish proximity (F1,14 = 0.2, p = 0.67). Post hoc multiple comparisons showed that F + S sea cucumbers had significantly lower levels of NEAAs after 3 months of IMTA compared with S sea cucumbers, but showed no other differences between the two treatments before that time point (Figure 6C). Relative levels of AMs, EAAs, NEAAs (muscle bands only), NPAAs, and OHCs in sea cucumber tissues were unaffected by fish proximity, duration of IMTA, or their interactions (Figure 6).

3.2.3. Unsupervised Hierarchical Clustering Analysis

Unsupervised hierarchical clustering analysis of 85 individual nitrogenous metabolites in the two sea cucumber tissue types revealed two clusters based on tissue type only: (1) body walls and (2) muscle bands (Figure 7, Table 2). Sea cucumber body walls were enriched with ethanolamine (HCPC, p = 0.016) and trigonelline (HCPC, p = 0.031) while the muscle bands were enriched with alanine, arginine, betaine, glutamic acid, and phenylalanine (Table 2; HCPC, p < 0.01). Sample location (farmed versus wild) and fish proximity (F + S versus S) did not have significant effects on the composition of nitrogenous metabolites in sea cucumber tissues.

4. Discussion

The present study explored the fatty-acid and nitrogenous-metabolite profiles of California sea cucumbers included in IMTA with Chinook salmon for 3 months. The fatty-acid profiles of farmed (F + S and S) sea cucumbers differed significantly from those of wild individuals, while the nitrogenous-metabolite profiles showed little change between farmed and wild individuals.
The fatty-acid profiles of farmed sea cucumbers differed from wild individuals with the presence of unique fatty acids like 6-docosapentaenoic acid (22:5n-6) and 11-eicosenoic acid (20:1n-11), which were not detected in wild individuals, and in having a higher relative percent of long-chain MUFAs. The presence of 22:5n-6 in farmed, but not wild, sea cucumbers can be explained by the former consuming fish wastes and commercial fish feed pellets during IMTA with the fish, since this fatty acid has been previously reported in Chinook salmon wastes [43], and it was present in the two commercial feeds used in the present study. Dietary PUFAs also tend to be accumulated by sea cucumbers when they are available [28]. Furthermore, 20:1n-11 is a common n-11 found in finfish oil, but it was not detected in the commercial fish feed pellets used during the present study. It is likely, then, that the farmed sea cucumbers obtained this fatty acid from feeding on fish wastes alone or were able to produce it by elongating shorter MUFAs [28]. Farmed sea cucumbers in the present study also had higher percent compositions of long-chain MUFAs than wild individuals, specifically driven by enriched levels of n-3 fatty acids like EPA (20:5n-3) and DHA (22:6n-3). This shift toward higher levels of long-chain MUFAs reflects the relative fatty-acid composition of the commercial feed used in the present study and patterns seen in farmed versus wild salmon tissues [44].
Interestingly, proximity to the fish during IMTA also affected the fatty-acid profiles of farmed sea cucumbers, with those housed directly in fish cages (F + S) showing the highest levels of MUFAs and enrichment of specific fatty acids found in commercial fish feed pellets from plant sources such as oleic acid (18:1n-9) and the essential fatty acid linoleic acid (18:2n-6 cis). The enrichment of these fatty acids originating from commercial feed (present study) and Chinook salmon waste [43] in the tissues of sea cucumbers in close proximity to farmed fish confirms they are feeding on those materials and acting as extractive species. Several other studies have also shown that California sea cucumbers can efficiently consume and assimilate both shellfish and finfish waste in IMTA [13,14,45]. A parallel study conducted at the same Chinook salmon farm sites as the present work found that S individuals fed on cage biofouling material as well as fish wastes and uneaten feed from neighboring upstream cages stocked with fish [25]. Those findings suggest that the placement of extractive species relative to primary species in IMTA needs to be considered carefully in order to achieve the specific goals of the partnership. If nutrient removal is the goal, the extractive species needs to be directly in contact with or directly downstream of the primary species, as simply placing them adjacent to the primary species may not be sufficient. Modern modeling techniques can be used to design effective open [15,46,47] and partially closed (limited water exchange) [2] IMTA systems, but this would require significantly more investment from industry at the front end to ensure proper placement of extractive species.
The presence of unique or enriched fatty acids in farmed sea cucumber tissues versus wild sea cucumber tissues could be used as biomarkers in future IMTA studies (see [19,48,49]). However, these markers may be applicable only for certain regions and certain times of the year, as 20:1n-11, one of the unique fatty acids found in the farmed sea cucumber tissues in the present study, has been reported in wild California sea cucumbers collected in the spring in Alaska [50]. Seasonal and regional variations in fatty-acid profiles are poorly understood for California sea cucumbers despite numerous studies highlighting the possibility for these differences in other commercial sea cucumber species. Seasonal changes in food sources and biochemical composition have been reported for A. japonicus, a closely related species to A. californicus [29,51], H. tubulosa [52], Holothuria leucospilota [53], and Cucumaria frondosa [54].
Like other stichopodids, California sea cucumbers undergo seasonal changes in their physiology, metabolism, and behavior as they enter into an annual dormancy period each winter. That period is characterized by resorption of the gut and reorganization of body tissues, including lipid reserves [25,55,56], and would need to be explored further before the commercialization of sea cucumber–Chinook IMTA would be viable. Studies directed at exploring the long-term nutritional changes in sea cucumbers in IMTA with finfish should therefore first assess the seasonal or regional variability of the biochemical composition in wild sea cucumber populations in order to understand how exposure to the farm environment could interact with those natural patterns.
The amino acids and other nitrogenous compounds explored in the present study did not differ substantially between the farmed and wild sea cucumbers. This is not surprising, as fatty acids and stable isotopes are recognized as being more sensitive indicators of dietary changes in aquaculture systems [48]. Another explanation could be the length of time the sea cucumbers in the present study were included in IMTA. Protein turnover occurs at a lower rate, so any changes in amino acid composition might not be detectable after only 3 months. The use of an isotope tracer to assess the rate of protein synthesis would be informative for future studies [57,58]. As with fatty-acid profiles, there is also likely a seasonal component to amino acid or metabolite composition that has not been encapsulated in the present work. For instance, a study of sea cucumber biochemical composition detected seasonal patterns in amino acid and mineral compositions in H. tubulosa when tissue samples were collected and analyzed over an entire year [52].
Shifts in stable isotope ratios have been reported for California sea cucumbers in IMTA with Chinook salmon as soon as 1 month after inclusion with fish [25] and after 4 months for H. poli held beneath sea bream and bass cages in the Mediterranean [7,19], which suggests that a change in sea cucumber composition (and potentially trophic position) can occur rapidly as a result of IMTA with finfish. In the present study, sea cucumbers may have been eating fish feces, sea cucumber feces, waste fish-feed pellets, or any combination of these. Concomitant research with the current study showed that sea cucumbers cultured with Chinook salmon showed slight shifts in dietary carbon source and trophic position (i.e., higher d15N enrichment). Those shifts would correspond with sea cucumbers feeding on a food source such as salmon pellets, high in organic wheat and fish extracts, but it does not rule out the possibility of consumption of fish feces or even sea cucumber feces (25). Further research is required to determine the actual food source of sea cucumbers when in co-culture with salmon.
Taken together with the fatty acid findings of the present study, these results support the notion that “you are what you eat” and reinforce the importance of considering nutritional changes in the tissues of extractive species in IMTA prior to commercialization. The presence of 11-eicosanoic acid and the enriched levels of EPA, DHA, oleic acid, and linoleic acid in farmed sea cucumbers in the present study is potentially quite interesting from a food-science perspective, as it could be another value-added benefit to including extractive species in IMTA with finfish if the sea cucumbers can gain some of the important biochemical properties of the fish with little additional effort. Sea cucumbers are already recognized as one of the most healthful and important luxury seafoods worldwide [59,60,61]. However, if inclusion in IMTA with finfish makes them even more healthful for humans and improves the sustainability of traditional aquaculture practice, they will continue to become even more lucrative and sought after, especially if their taste remains similar or improves as a result of their changing fatty acid profiles in IMTA. Future research should examine the effects of IMTA with salmon on the flavor and texture properties of sea cucumbers.

5. Conclusions

The results of the study indicated significant changes in the fatty-acid profiles of the body walls and muscle bands of adult California sea cucumbers grown with Chinook salmon compared with wild reference individuals. Sea cucumbers cultured with the fish had higher levels of MUFAs and lower concentrations of SFAs than their reference counterparts, while PUFA levels were essentially the same in the two populations. Few differences were detected between the treatment and reference individuals in various amino acids and other nitrogenous metabolites. The results may have implications for human health, as the sea cucumbers cultured with the salmon shifted away from certain saturated to unsaturated fatty acids.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/fishes10040154/s1, Table S1. (Relative percent (%) composition of fatty acids in sea cucumber tissues (body walls (BW), muscle bands (MB)) after 3-month inclusion in IMTA with Chinook salmon versus wild sea cucumbers collected from a reference site), Table S2. (Relative percent (%) composition of proteinogenic amino acids in sea cucumber tissues (body walls (BW), muscle bands (MB)) after 3-month inclusion in IMTA with Chinook salmon versus wild sea cucumbers collected from a reference site).

Author Contributions

Conceptualization, E.M.M. and C.M.P.; methodology, E.M.M., C.M.P., I.P.F. and M.N.; software, E.M.M.; validation, E.M.M. and C.M.P.; formal analysis, E.M.M.; investigation, E.M.M. and M.N.; resources, B.L.C., I.P.F. and C.M.P.; data curation, E.M.M., M.N. and C.M.P.; writing—original draft preparation, E.M.M.; writing—review and editing, E.M.M., B.L.C., M.N., R.B.L., I.P.F. and C.M.P.; visualization, E.M.M.; supervision, C.M.P.; project administration, E.M.M., B.L.C., I.P.F. and C.M.P.; funding acquisition, E.M.M. and C.M.P. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Aquaculture Collaborative Research and Development Program (ACRDP) of Fisheries and Oceans Canada (grant number ACRDP 20-P-05) and Creative Salmon Co., Ltd. (Tofino, BC, Canada).

Institutional Review Board Statement

The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Institutional Review Board (Pacific Region Animal Care Committee) of Fisheries and Oceans Canada, Pacific Biological Station (AUP 21-005, approved 13 April 2021).

Informed Consent Statement

Not applicable.

Data Availability Statement

The data are not publicly available.

Acknowledgments

Funding and in-kind support was provided by the Aquaculture Collaborative Research and Development Program (ACRDP, Project: 20-P-05) of Fisheries and Oceans Canada and Creative Salmon Co., Ltd. (Tofino, BC, Canada). The authors thank the field crews of Creative Salmon Co., Ltd. and the dive team at Mulder Marine for their enthusiasm and facilitation of the work at the farm sites. The authors also thank Tim Green and Sarah Leduc at the Deep Bay Marine Field Station of Vancouver Island University for hosting them for preliminary laboratory tests on sea cucumber escapement, UB Diving for collecting sea cucumbers, and the Genome British Columbia Proteomics Centre at the University of Victoria for conducting the metabolomics work.

Conflicts of Interest

The authors declare that this study received funding from Creative Salmon Co., Ltd. (Tofino, BC, Canada) and that two authors, Barb L. Cannon and Rodrigo B. Leme, were employed by Creative Salmon Co., Ltd. at the time of the project. The company provided funding and resources for the research, and Barb L. Cannon and Rodrigo B. Leme participated in the final review of the manuscript. They were not, however, involved in the processing/interpretation of the data.

References

  1. Hossain, A.; Senff, P.; Glaser, M. Lessons for Coastal Applications of IMTA as a Way towards Sustainable Development: A Review. Appl. Sci. 2022, 12, 11920. [Google Scholar] [CrossRef]
  2. Khanjani, M.H.; Zahedi, S.; Mohammadi, A. Integrated Multitrophic Aquaculture (IMTA) as an Environmentally Friendly System for Sustainable Aquaculture: Functionality, Species, and Application of Biofloc Technology (BFT). Environ. Sci. Pollut. Res. 2022, 29, 67513–67531. [Google Scholar] [CrossRef]
  3. Liu, Y.; Zhang, J.; Wu, W.; Zhong, Y.; Li, H.; Wang, X.; Yang, J.; Zhang, Y. Effects of Shellfish and Macro-Algae IMTA in North China on the Environment, Inorganic Carbon System, Organic Carbon System, and Sea–Air CO2 Fluxes. Front. Mar. Sci. 2022, 9, 864306. [Google Scholar] [CrossRef]
  4. Joseph, S.; Ignatius, B.; Joseph, I.; Rajesh, N. Integrated Multitrophic Aquaculture (IMTA)—A Successful Diversified Farming System. In Winter School on Mariculture Technologies for Income Multiplication, Employment, Livelihood and Empowerment; ICAR-Central Marine Fisheries Research Institute: Kochi, India, 2023; pp. 53–61. [Google Scholar]
  5. Chopin, T.; Robinson, S.; Reid, G.; Ridler, N. Prospects for Integrated Multi-Trophic Aquaculture (IMTA) in the Open Ocean. Bull. Aquac. Assoc. Can. 2013, 111–112, 28–35. [Google Scholar]
  6. Chary, K.; Aubin, J.; Sadoul, B.; Fiandrino, A.; Covès, D.; Callier, M.D. Integrated Multi-Trophic Aquaculture of Red Drum (Sciaenops ocellatus) and Sea Cucumber (Holothuria scabra): Assessing Bioremediation and Life-Cycle Impacts. Aquaculture 2020, 516, 734621. [Google Scholar] [CrossRef]
  7. Cutajar, K.; Falconer, L.; Massa-Gallucci, A.; Cox, R.E.; Schenke, L.; Bardócz, T.; Sharman, A.; Deguara, S.; Telfer, T.C. Culturing the Sea Cucumber Holothuria poli in Open-Water Integrated Multi-Trophic Aquaculture at a Coastal Mediterranean Fish Farm. Aquaculture 2022, 550, 737881. [Google Scholar] [CrossRef]
  8. Mazón-Suástegui, J.M.; Arcos-Ortega, G.F.; Contreras-Mendoza, C.N.; Medina-Sánchez, J.R.; Chávez-Villalba, J.; Lodeiros, C.; Cruz-Flores, R.; López-Carvallo, J.A. Enhanced Growth of the Pleasure Oyster Crassostrea corteziensis Cultured under Integrated Multi-Trophic Aquaculture (IMTA) Concept, Using Farm Effluents of Shrimp Penaeus vannamei. Aquac. Res. 2022, 53, 5214–5226. [Google Scholar] [CrossRef]
  9. Grosso, L.; Rakaj, A.; Fianchini, A.; Morroni, L.; Cataudella, S.; Scardi, M. Integrated Multi-Trophic Aquaculture (IMTA) System Combining the Sea Urchin Paracentrotus lividus, as Primary Species, and the Sea Cucumber Holothuria tubulosa as Extractive Species. Aquaculture 2021, 534, 736268. [Google Scholar] [CrossRef]
  10. Troell, M.; Joyce, A.; Chopin, T.; Neori, A.; Buschmann, A.H.; Fang, J.G. Ecological Engineering in Aquaculture—Potential for Integrated Multi-Trophic Aquaculture (IMTA) in Marine Offshore Systems. Aquaculture 2009, 297, 1–9. [Google Scholar] [CrossRef]
  11. Orr, L.C.; Curtis, D.L.; Cross, S.F.; Gurney-Smith, H.; Shanks, A.; Pearce, C.M. Ingestion Rate, Absorption Efficiency, Oxygen Consumption, and Fecal Production in Green Sea Urchins (Strongylocentrotus droebachiensis) Fed Waste from Sablefish (Anoplopoma fimbria) Culture. Aquaculture 2014, 422–423, 184–192. [Google Scholar] [CrossRef]
  12. Fossberg, J.; Forbord, S.; Broch, O.J.; Malzahn, A.M.; Jansen, H.; Handå, A.; Førde, H.; Bergvik, M.; Fleddum, A.L.; Skjermo, J.; et al. The Potential for Upscaling Kelp (Saccharina latissima) Cultivation in Salmon-Driven Integrated Multi-Trophic Aquaculture (IMTA). Front. Mar. Sci. 2018, 9, 418. [Google Scholar] [CrossRef]
  13. Paltzat, D.L.; Pearce, C.M.; Barnes, P.A.; McKinley, R.S. Growth and Production of California Sea Cucumbers (Parastichopus californicus Stimpson) Co-Cultured with Suspended Pacific Oysters (Crassostrea gigas Thunberg). Aquaculture 2008, 275, 124–137. [Google Scholar] [CrossRef]
  14. Hannah, L.; Pearce, C.M.; Cross, S.F. Growth and Survival of California Sea Cucumbers (Parastichopus californicus) Cultivated with Sablefish (Anoplopoma fimbria) at an Integrated Multi-Trophic Aquaculture Site. Aquaculture 2013, 406–407, 34–42. [Google Scholar] [CrossRef]
  15. Cubillo, A.M.; Ferreira, J.G.; Robinson, S.M.C.; Pearce, C.M.; Corner, R.A.; Johansen, J. Role of Deposit Feeders in Integrated Multi-Trophic Aquaculture—A Model Analysis. Aquaculture 2016, 453, 54–66. [Google Scholar] [CrossRef]
  16. Zamora, L.N.; Yuan, X.; Carton, A.G.; Slater, M.J. Role of Deposit-Feeding Sea Cucumbers in Integrated Multitrophic Aquaculture: Progress, Problems, Potential and Future Challenges. Rev. Aquac. 2018, 10, 57–74. [Google Scholar] [CrossRef]
  17. Yang, H.; Hamel, J.-F.; Mercier, A. The Sea Cucumber Apostichopus japonicus: History, Biology and Aquaculture; Academic Press: Cambridge, MA, USA, 2015; ISBN 0128004673. [Google Scholar]
  18. MacDonald, C.L.E.; Stead, S.M.; Slater, M.J. Consumption and Remediation of European Seabass (Dicentrarchus labrax) Waste by the Sea Cucumber Holothuria forskali. Aquac. Int. 2013, 21, 1279–1290. [Google Scholar] [CrossRef]
  19. Cutajar, K.; Falconer, L.; Massa-Gallucci, A.; Cox, R.E.; Schenke, L.; Bardócz, T.; Andolina, C.; Signa, G.; Vizzini, S.; Sprague, M.; et al. Stable Isotope and Fatty Acid Analysis Reveal the Ability of Sea Cucumbers to Use Fish Farm Waste in Integrated Multi-Trophic Aquaculture. J. Environ. Manag. 2022, 318, 115511. [Google Scholar] [CrossRef]
  20. Sadoul, B.; Caprioli, J.-P.; Barrier-Loiseau, C.; Cimiterra, N.; Laugier, T.; Lagarde, F.; Chary, K.; Callier, M.D.; Guillermard, M.-O.; Roque d’Orbcastel, E. Is Holothuria tubulosa the Golden Goose of Ecological Aquaculture in the Mediterranean Sea? Aquaculture 2022, 554, 738149. [Google Scholar] [CrossRef]
  21. Tolon, M.T.; Emiroğlu, D.; Günay, D.; Özgül, A. Sea Cucumber (Holothuria tubulosa Gmelin, 1790) Culture under Marine Fish Net Cages for Potential Use in Integrated Multi-Trophic Aquaculture (IMTA). Indian J. Geo-Mar. Sci. 2017, 46, 749–756. [Google Scholar]
  22. Nelson, E.J.; MacDonald, B.A.; Robinson, S.M.C. The Absorption Efficiency of the Suspension-Feeding Sea Cucumber, Cucumaria frondosa, and its Potential as an Extractive Integrated Multi-Trophic Aquaculture (IMTA) Species. Aquaculture 2012, 370–371, 19–25. [Google Scholar] [CrossRef]
  23. Sun, J.; Hamel, J.-F.; Gianasi, B.L.; Graham, M.; Mercier, A. Growth, Health and Biochemical Composition of the Sea Cucumber Cucumaria frondosa after Multi-Year Holding in Effluent Waters of Land-Based Salmon Culture. Aquac. Environ. Interact. 2020, 12, 139–151. [Google Scholar] [CrossRef]
  24. Haddad, C.A.; Cross, S.F.; Davies, H.L.; Duff, S.D.; Fortune, A.C.; Pearce, C.M. Assessing Natural Substrates for Restricting Movement of California Sea Cucumbers Parastichopus californicus. N. Am. J. Aquac. 2018, 80, 347–354. [Google Scholar] [CrossRef]
  25. Montgomery, E.M.; Cannon, B.L.; Pearce, C.M. Exploring Biofouling Control by the California Sea Cucumber (Apostichopus californicus) in Integrated Multi-Trophic Aquaculture (IMTA) with Organic Chinook Salmon (Oncorhynchus tshawytscha). Fishes 2023, 8, 430. [Google Scholar] [CrossRef]
  26. Curtis, D.L.; Pearce, C.M.; van Dam-Bates, P.; Duprey, N.M.T.; Cross, S.F.; Cowen, L.L.E. California Sea Cucumber (Apostichopus californicus) Abundance and Movement on a Commercial Shellfish Aquaculture Farm. Diversity 2023, 15, 940. [Google Scholar] [CrossRef]
  27. Montgomery, E.M.; Suhrbier, A.D.; Pearce, C.M. Biology, Ecology, Aquaculture, and Commercial Products of Apostichopus californicus. In The World of Sea Cucumbers: Challenges, Advances, and Innovations; Elsevier: Amsterdam, The Netherlands, 2024; pp. 653–675. [Google Scholar]
  28. Yokoyama, H.; Tadokoro, D.; Miura, M. Quantification of Waste Feed and Fish Faeces in Sediments beneath Yellowtail Pens and Possibility to Reduce Waste Loading by Co-Culturing with Sea Cucumbers: An Isotopic Study. Aquac. Res. 2015, 46, 918–927. [Google Scholar] [CrossRef]
  29. Imbs, A.B.; Svetashev, V.I.; Rodkina, S.A. Differences in Lipid Class and Fatty Acid Composition between Wild and Cultured Sea Cucumbers, Apostichopus japonicus, Explain Modification and Deposition of Lipids. Aquac. Res. 2022, 53, 810–819. [Google Scholar] [CrossRef]
  30. Feng, J.; Zhang, L.; Tang, X.; Xia, X.; Hu, W.; Zhou, P. Season and Geography Induced Variation in Sea Cucumber (Stichopus japonicus) Nutritional Composition and Gut Microbiota. J. Food Compos. Anal. 2021, 101, 103838. [Google Scholar] [CrossRef]
  31. Jiang, W.-D.; Wu, P.; Tang, R.-J.; Liu, Y.; Kuang, S.-Y.; Jiang, J.; Tang, L.; Tang, W.-N.; Zhang, Y.-A.; Zhou, X.-Q.; et al. Nutritive Values, Flavor Amino Acids, Healthcare Fatty Acids and Flesh Quality Improved by Manganese Referring to up-Regulating the Antioxidant Capacity and Signaling Molecules TOR and Nrf2 in the Muscle of Fish. Food Res. Int. 2016, 89, 670–678. [Google Scholar]
  32. Peinado, I.; Miles, W.; Koutsidis, G. Odour Characteristics of Seafood Flavour Formulations Produced with Fish By-Products Incorporating EPA, DHA and Fish Oil. Food Chem. 2016, 212, 612–619. [Google Scholar]
  33. Hajas, W.; Hand, C.; Duprey, N.; Lochead, J.; Deault, J. Using Production Models with New and Developing Fisheries: A Case Study Using the Sea Cucumber Parastichopus californicus in British Columbia, Canada. Fish. Res. 2011, 110, 421–434. [Google Scholar] [CrossRef]
  34. Lochead, J.; Ridings, P.; Hansen, S.C. Ensuring Long-Term Sustainability of the Fishery for Apostichopus californicus in British Columbia (Canada) through Collaborative Science and Adaptive Management. In The World of Sea Cucumbers: Challenges, Advances, and Innovations; Elsevier: Amsterdam, The Netherlands, 2024; pp. 677–685. [Google Scholar]
  35. Ahlgren, M.O. Consumption and Assimilation of Salmon Net Pen Fouling Debris by the Red Sea Cucumber Parastichopus californicus: Implications for Polyculture. J. World Aquac. Soc. 1998, 29, 133–139. [Google Scholar] [CrossRef]
  36. Puttick, D.; Dauk, M.; Lozinsky, S.; Smith, M.A. Overexpression of a FAD3 Desaturase Increases Synthesis of a Polymethylene-Interrupted Dienoic Fatty Acid in Seeds of Arabidopsis thaliana L. Lipids 2009, 44, 753–757. [Google Scholar]
  37. R Core Team. R: A Language and Environment for Statistical Computing 2024. R Foundation for Statistical Computing, Vienna, Austria. Available online: https://www.R-project.org/ (accessed on 11 March 2025).
  38. Wickham, H. Ggplot2; Use R! Springer International Publishing: London, UK, 2016; ISBN 978-3-319-24275-0. [Google Scholar]
  39. Leys, C.; Schumann, S. A Nonparametric Method to Analyze Interactions: The Adjusted Rank Transform Test. J. Exp. Soc. Psychol. 2010, 46, 684–688. [Google Scholar] [CrossRef]
  40. Wobbrock, J.O.; Findlater, L.; Gergle, D.; Higgins, J.J. The Aligned Rank Transform for Nonparametric Factorial Analyses Using Only ANOVA Procedures. In Proceedings of the Conference on Human Factors in Computing Systems—Proceedings 2011, Vancouver, BC, Canada, 7–12 May 2011; pp. 143–146. [Google Scholar] [CrossRef]
  41. Khoomrung, S.; Raber, G.; Laoteng, K.; Francesconi, K.A. Identification and Characterization of Fish Oil Supplements Based on Fatty Acid Analysis Combined with a Hierarchical Clustering Algorithm. Eur. J. Lipid Sci. Technol. 2014, 116, 795–804. [Google Scholar] [CrossRef]
  42. Husson, F.; Josse, J.; Le, S.; Mazet, J.; Husson, M.F. Package ‘Factominer’. R. Package 2016, 96, 698. [Google Scholar]
  43. Elvines, D.M.; MacLeod, C.K.; Ross, D.J.; Hopkins, G.A.; White, C.A. Fate and Effects of Fish Farm Organic Waste in Marine Systems: Advances in Understanding Using Biochemical Approaches with Implications for Environmental Management. Rev. Aquac. 2023, 16, 66–85. [Google Scholar] [CrossRef]
  44. Sissener, N.H. Are We What We Eat? Changes to the Feed Fatty Acid Composition of Farmed Salmon and its Effects through the Food Chain. J. Exp. Biol. 2018, 221 (Suppl. S1), jeb161521. [Google Scholar]
  45. Orr, L.C. Co-Culture of Invertebrates with Sablefish (Anoplopoma fimbria) in IMTA in British Columbia: Use of Laboratory Feeding Trials to Assess the Organic Extractive Potential of Various Candidate Species. MSc Thesis, University of Victoria, Victoria, BC, Canada, 2012. [Google Scholar]
  46. Robinson, S.M.C.; Martin, J.D.; Cooper, J.A.; Lander, T.R.; Reid, G.K.; Powell, F.; Griffin, R. The Role of Three Dimensional Habitats in the Establishment of Integrated Multi-Trophic Aquaculture (IMTA) Systems. Bull. Aquac. Assoc. Can. 2011, 109, 23–29. [Google Scholar]
  47. Reid, G.K.; Lefebvre, S.; Filgueira, R.; Robinson, S.M.C.; Broch, O.J.; Dumas, A.; Chopin, T.B.R. Performance Measures and Models for Open-Water Integrated Multi-Trophic Aquaculture. Rev. Aquac. 2020, 12, 47–75. [Google Scholar] [CrossRef]
  48. Irisarri, J.; Fernández-Reiriz, M.J.; Labarta, U.; Cranford, P.J.; Robinson, S.M.C. Availability and Utilization of Waste Fish Feed by Mussels Mytilus edulis in a Commercial Integrated Multi-Trophic Aquaculture (IMTA) System: A Multi-Indicator Assessment Approach. Ecol. Indic. 2015, 48, 673–686. [Google Scholar] [CrossRef]
  49. Nahon, S.; de Brito, G.V.; Quental-Ferreira, H.; Aubin, J.; Jaeger, C.; Menniti, C.; Kerhervé, P.; Larroquet, L.; Cunha, M.E. Food Web in Mediterranean Coastal Integrated Multi-Trophic Aquaculture Ponds: Learnings from Fatty Acids and Stable Isotope Tracers. Aquaculture 2023, 567, 739292. [Google Scholar] [CrossRef]
  50. Bechtel, P.J.; Oliveira, A.C.M.; Demir, N.; Smiley, S. Chemical Composition of the Giant Red Sea Cucumber, Parastichopus californicus, Commercially Harvested in Alaska. Food Sci. Nutr. 2013, 1, 63–73. [Google Scholar] [CrossRef]
  51. Gao, F.; Xu, Q.; Yang, H. Seasonal Biochemical Changes in Composition of Body Wall Tissues of Sea Cucumber Apostichopus japonicus. Chinese J. Oceanol. Limnol. 2011, 29, 252–260. [Google Scholar] [CrossRef]
  52. Künili, I.E.; Çolakoğlu, F.A. Chemical and Nutritional Characteristics of Holothuria tubulosa (Gmelin, 1788); A Seasonally Comparative Study. J. Aquat. Food Prod. Technol. 2019, 28, 716–728. [Google Scholar] [CrossRef]
  53. Hafezieh, M.; Jamili, S.; Dadgar, S. Changes of Sea Cucumber (Holothuria leucospilota) Proximate Composition during Geographical-Seasonal Variation in the Persian Gulf and Oman Sea Waters. Iran. Sci. Fish. J. 2018, 27, 13–24. [Google Scholar]
  54. Abuzaytoun, R.; Budge, S.M.; Xia, W.; Mackinnon, S. Unusual Ether Lipids and Branched Chain Fatty Acids in Sea Cucumber (Cucumaria frondosa) Viscera and Their Seasonal Variation. Mar. Drugs 2022, 20, 435. [Google Scholar] [CrossRef]
  55. Fankboner, P.V. Seasonal Visceral Atrophy and Response to Salinity by Parastichopus californicus. SPC Beche-de-mer Inf. Bull. 2002, 17, 22–26. [Google Scholar]
  56. Fankboner, P.V.; Cameron, J.L. Seasonal Atrophy of the Visceral Organs in a Sea Cucumber. Can. J. Zool. 1985, 63, 2888–2892. [Google Scholar] [CrossRef]
  57. Sveier, H.; Raae, A.J.; Lied, E. Growth and Protein Turnover in Atlantic Salmon (Salmo salar L.); the Effect of Dietary Protein Level and Protein Particle Size. Aquaculture 2000, 185, 101–120. [Google Scholar] [CrossRef]
  58. Morais, S.; Koven, W.; Rønnestad, I.; Dinis, M.T.; Conceição, L.E.C. Dietary Protein/Lipid Ratio Affects Growth and Amino Acid and Fatty Acid Absorption and Metabolism in Senegalese Sole (Solea senegalensis Kaup 1858) Larvae. Aquaculture 2005, 246, 347–357. [Google Scholar] [CrossRef]
  59. Bordbar, S.; Anwar, F.; Saari, N. High-Value Components and Bioactives from Sea Cucumbers for Functional Foods—A Review. Mar. Drugs 2011, 9, 1761–1805. [Google Scholar] [CrossRef] [PubMed]
  60. Purcell, S. Value, Market Preferences and Trade of Beche-De-Mer from Pacific Island Sea Cucumbers. PLoS ONE 2014, 9, e95075. [Google Scholar] [CrossRef]
  61. Purcell, S.; Conand, C.; Uthicke, S.; Byrne, M. Ecological Roles of Exploited Sea Cucumbers. Oceanogr. Mar. Biol. Ann. Rev. 2016, 54, 367–386. [Google Scholar]
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Figure 1. (A) Map showing western North America and Vancouver Island, British Columbia (BC), Canada, where the study took place. The dotted white line indicates the border between Canada and the United States of America and the green square shows the general area where the research was conducted. (B) Map showing Chinook salmon farm locations used for the project in Clayoquot Sound, BC. Farm sites are indicated by yellow squares (DP = Dawley Pass, WI = Warne Island). The sea cucumber collection site (and wild reference site) is shown by a blue triangle.
Figure 1. (A) Map showing western North America and Vancouver Island, British Columbia (BC), Canada, where the study took place. The dotted white line indicates the border between Canada and the United States of America and the green square shows the general area where the research was conducted. (B) Map showing Chinook salmon farm locations used for the project in Clayoquot Sound, BC. Farm sites are indicated by yellow squares (DP = Dawley Pass, WI = Warne Island). The sea cucumber collection site (and wild reference site) is shown by a blue triangle.
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Figure 2. Relative composition (%) of three categories of fatty acids in sea cucumber body walls (BW) and muscle bands (MB) after 3-month inclusion in Chinook salmon IMTA (dark gray boxes, Farm) and in wild sea cucumber reference samples collected >1 km away from the farm sites (white boxes, Wild) in the same month (October). The categories of fatty acids included (A) saturated (SFA), (B) monounsaturated (MUFA), and (C) polyunsaturated (PUFA). Different upper-case letters indicate significant differences between treatments when there were significant main effects (sea cucumber treatment or tissue type) but no significant interaction. Different lower-case letters indicate significant differences between treatments when there was a significant interaction between the factors. Bottom whiskers indicate the first quartile, while top whiskers indicate the fourth quartile. Boxes include the second and third quartiles separated by the median (thicker black line).
Figure 2. Relative composition (%) of three categories of fatty acids in sea cucumber body walls (BW) and muscle bands (MB) after 3-month inclusion in Chinook salmon IMTA (dark gray boxes, Farm) and in wild sea cucumber reference samples collected >1 km away from the farm sites (white boxes, Wild) in the same month (October). The categories of fatty acids included (A) saturated (SFA), (B) monounsaturated (MUFA), and (C) polyunsaturated (PUFA). Different upper-case letters indicate significant differences between treatments when there were significant main effects (sea cucumber treatment or tissue type) but no significant interaction. Different lower-case letters indicate significant differences between treatments when there was a significant interaction between the factors. Bottom whiskers indicate the first quartile, while top whiskers indicate the fourth quartile. Boxes include the second and third quartiles separated by the median (thicker black line).
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Figure 3. Relative composition (%) of three categories of fatty acids in sea cucumber body walls (BW) and muscle bands (MB) after 1-, 2-, and 3-month inclusion in Chinook salmon IMTA. White boxes indicate sea cucumbers that were housed in cages with no fish (S), while gray boxes show sea cucumbers that were kept in cages with fish (F + S). The categories of fatty acids included (A) saturated (SFA), (B) monounsaturated (MUFA), and (C) polyunsaturated (PUFA). Different lower-case letters indicate significant differences between treatments when there was a significant interaction between the factors (fish proximity and IMTA duration). Bottom whiskers indicate the first quartile, while top whiskers indicate the fourth quartile. Boxes include the second and third quartiles separated by the median (thicker black line). The • symbol represents outliers outside the first and fourth quartiles.
Figure 3. Relative composition (%) of three categories of fatty acids in sea cucumber body walls (BW) and muscle bands (MB) after 1-, 2-, and 3-month inclusion in Chinook salmon IMTA. White boxes indicate sea cucumbers that were housed in cages with no fish (S), while gray boxes show sea cucumbers that were kept in cages with fish (F + S). The categories of fatty acids included (A) saturated (SFA), (B) monounsaturated (MUFA), and (C) polyunsaturated (PUFA). Different lower-case letters indicate significant differences between treatments when there was a significant interaction between the factors (fish proximity and IMTA duration). Bottom whiskers indicate the first quartile, while top whiskers indicate the fourth quartile. Boxes include the second and third quartiles separated by the median (thicker black line). The • symbol represents outliers outside the first and fourth quartiles.
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Figure 4. Unsupervised hierarchical clustering of principal components (HCPC) to explore the composition patterns of fatty acids in sea cucumber tissues after 3-month inclusion in IMTA with Chinook salmon. Wild reference samples were also included in the analysis. Thirty-one unique fatty acids belonging to three different classes were used for the HCPC (e.g., various saturated, monounsaturated, and polyunsaturated fatty acids). The most parsimonious clustering pattern revealed seven clusters based on tissue type and treatment (sea cucumbers with (F + S) or without (S) fish and wild reference sea cucumbers). (1) F + S muscle bands (MB, brown squares), (2) S muscle bands (orange circles), (3) F + S body walls (BW, black triangles), (4) S body walls (gray diamonds), (5) commercial salmon food (blue plus signs), (6) wild muscle bands (green x’s), and (7) wild body walls (purple asterisks). See Table 1 for details on the clusters. Ellipses indicate 95% confidence intervals based on the most parsimonious clustering pattern.
Figure 4. Unsupervised hierarchical clustering of principal components (HCPC) to explore the composition patterns of fatty acids in sea cucumber tissues after 3-month inclusion in IMTA with Chinook salmon. Wild reference samples were also included in the analysis. Thirty-one unique fatty acids belonging to three different classes were used for the HCPC (e.g., various saturated, monounsaturated, and polyunsaturated fatty acids). The most parsimonious clustering pattern revealed seven clusters based on tissue type and treatment (sea cucumbers with (F + S) or without (S) fish and wild reference sea cucumbers). (1) F + S muscle bands (MB, brown squares), (2) S muscle bands (orange circles), (3) F + S body walls (BW, black triangles), (4) S body walls (gray diamonds), (5) commercial salmon food (blue plus signs), (6) wild muscle bands (green x’s), and (7) wild body walls (purple asterisks). See Table 1 for details on the clusters. Ellipses indicate 95% confidence intervals based on the most parsimonious clustering pattern.
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Figure 5. Relative composition (%) of five categories of nitrogenous metabolites in sea cucumber body walls (BW) and muscle bands (MB) after 3-month inclusion in Chinook salmon IMTA (dark gray boxes, Farm) and in wild sea cucumber reference samples collected > 1 km away from the farm sites (white boxes, Wild) in the same month (October). The categories of metabolites included (A) amines (AM), (B) essential amino acids (EAA), (C) non-essential amino acids (NEAA), (D) non-proteinogenic amino acids (NPAA), and (E) organoheterocyclics (OHC). Different upper-case letters indicate significant differences between treatments when there were significant main effects (sea cucumber treatment or tissue type) but no significant interaction. Bottom whiskers indicate the first quartile, while top whiskers indicate the fourth quartile. Boxes include the second and third quartiles separated by the median (thicker black line). The • symbol represents outliers outside the first and fourth quartiles.
Figure 5. Relative composition (%) of five categories of nitrogenous metabolites in sea cucumber body walls (BW) and muscle bands (MB) after 3-month inclusion in Chinook salmon IMTA (dark gray boxes, Farm) and in wild sea cucumber reference samples collected > 1 km away from the farm sites (white boxes, Wild) in the same month (October). The categories of metabolites included (A) amines (AM), (B) essential amino acids (EAA), (C) non-essential amino acids (NEAA), (D) non-proteinogenic amino acids (NPAA), and (E) organoheterocyclics (OHC). Different upper-case letters indicate significant differences between treatments when there were significant main effects (sea cucumber treatment or tissue type) but no significant interaction. Bottom whiskers indicate the first quartile, while top whiskers indicate the fourth quartile. Boxes include the second and third quartiles separated by the median (thicker black line). The • symbol represents outliers outside the first and fourth quartiles.
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Figure 6. Relative composition (%) of five categories of nitrogenous metabolites in sea cucumber body walls (BW) and muscle bands (MB) after 1-, 2-, and 3-month inclusion in Chinook salmon IMTA. White boxes indicate sea cucumbers that were housed in cages with no fish (S), while gray boxes show sea cucumbers that were kept in cages with fish (F + S). The categories of metabolites included (A) amines (AM), (B) essential amino acids (EAA), (C) non-essential amino acids (NEAA), (D) non-proteinogenic amino acids (NPAA), and (E) organoheterocyclics (OHC). Different lower-case letters indicate significant differences between treatments when there was a significant interaction between the factors (fish proximity and IMTA duration). Bottom whiskers indicate the first quartile, while top whiskers indicate the fourth quartile. Boxes include the second and third quartiles separated by the median (thicker black line). The • symbol represents outliers outside the first and fourth quartiles.
Figure 6. Relative composition (%) of five categories of nitrogenous metabolites in sea cucumber body walls (BW) and muscle bands (MB) after 1-, 2-, and 3-month inclusion in Chinook salmon IMTA. White boxes indicate sea cucumbers that were housed in cages with no fish (S), while gray boxes show sea cucumbers that were kept in cages with fish (F + S). The categories of metabolites included (A) amines (AM), (B) essential amino acids (EAA), (C) non-essential amino acids (NEAA), (D) non-proteinogenic amino acids (NPAA), and (E) organoheterocyclics (OHC). Different lower-case letters indicate significant differences between treatments when there was a significant interaction between the factors (fish proximity and IMTA duration). Bottom whiskers indicate the first quartile, while top whiskers indicate the fourth quartile. Boxes include the second and third quartiles separated by the median (thicker black line). The • symbol represents outliers outside the first and fourth quartiles.
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Figure 7. Unsupervised hierarchical clustering of principal components (HCPC) to explore the composition patterns of nitrogenous metabolites in sea cucumber tissues after 3-month inclusion in IMTA with Chinook salmon. Wild reference samples were also included in the analysis. Eighty-five unique metabolites belonging to five different classes were used for the HCPC (e.g., amines, essential amino acids, non-essential amino acids, non-proteinogenic amino acids, and organoheterocyclics). The most parsimonious clustering pattern revealed two clusters based solely on tissue type: (1) body walls (black circles) and (2) muscle bands (gray triangles). See Table 2 for details on the clusters. No other factors influenced the clusters, including length of inclusion in IMTA or wild reference versus IMTA samples. Ellipses indicate 95% confidence intervals based on the most parsimonious clustering pattern.
Figure 7. Unsupervised hierarchical clustering of principal components (HCPC) to explore the composition patterns of nitrogenous metabolites in sea cucumber tissues after 3-month inclusion in IMTA with Chinook salmon. Wild reference samples were also included in the analysis. Eighty-five unique metabolites belonging to five different classes were used for the HCPC (e.g., amines, essential amino acids, non-essential amino acids, non-proteinogenic amino acids, and organoheterocyclics). The most parsimonious clustering pattern revealed two clusters based solely on tissue type: (1) body walls (black circles) and (2) muscle bands (gray triangles). See Table 2 for details on the clusters. No other factors influenced the clusters, including length of inclusion in IMTA or wild reference versus IMTA samples. Ellipses indicate 95% confidence intervals based on the most parsimonious clustering pattern.
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Table 1. Results from unsupervised hierarchical clustering of principal components (HCPC) to explore composition patterns of fatty acids (saturated = SFAs, monounsaturated = MUFAs, polyunsaturated = PUFAs) in sea cucumber tissues (body walls and muscle bands) after 3 months of IMTA in cages with fish (Chinook salmon = F + S) or without fish (S) and wild sea cucumbers collected from a reference site. Results of commercial salmon food are also included.
Table 1. Results from unsupervised hierarchical clustering of principal components (HCPC) to explore composition patterns of fatty acids (saturated = SFAs, monounsaturated = MUFAs, polyunsaturated = PUFAs) in sea cucumber tissues (body walls and muscle bands) after 3 months of IMTA in cages with fish (Chinook salmon = F + S) or without fish (S) and wild sea cucumbers collected from a reference site. Results of commercial salmon food are also included.
HCPC ClusterEnriched Fatty Acids Relative to Overall Meanp-Value
F + S
muscle bands		SFAs (none)
MUFAs (20:1n9, 22:1n-9, 24:1n-9)
PUFAs (20:2n-6, 20:4n-6, 22:5n-3, 22:5n-6, 22:6n-3)		All < 0.01
S
muscle bands		SFAs (none)
MUFAs (20:1n-9, 20:1n-11, 22:1n-11, 24:1n-9)
PUFAs (20:4n-6, 20:5n-3, 22:5n-6)		All < 0.01
Wild
muscle bands		SFAs (20:0, 21:0, 22:0)
MUFAs (none)
PUFAs (16:4n-1, 22:4n-6)		All < 0.01
F + S
body walls		SFAs (none)
MUFAs (18:1n-9)
PUFAs (18:2n-6, 22:5n-3, 22:6n-3)		All < 0.01
S
body walls		SFAs (15:0, 16:0, 17:0)
MUFAs (16:1n-7, 20:1n-11)
PUFAs (16:3n-4)		All < 0.01
Wild
body walls		SFAs (15:0, 20:0, 21:0, 22:0)
MUFAs (none)
PUFAs (16:2n-4, 18:3n-6)		All < 0.01
Commercial
salmon food		SFAs (14:0)
MUFAs (17:1, 18:1n-7)
PUFAs (18:2n-6, 18:3n-3, 18:4n-3)		All < 0.01
Table 2. Results from unsupervised hierarchical clustering of principal components (HCPC) to explore composition patterns of nitrogenous metabolites in sea cucumber tissues (body walls and muscle bands) during IMTA with Chinook salmon.
Table 2. Results from unsupervised hierarchical clustering of principal components (HCPC) to explore composition patterns of nitrogenous metabolites in sea cucumber tissues (body walls and muscle bands) during IMTA with Chinook salmon.
HCPC ClusterEnriched Metabolites Relative to Overall MeanMetabolite Typep-Value
Body wallsEthanolamine
Trigonelline		Amine
Organoheterocyclic		Both < 0.05
Muscle bandsAlanine
Arginine
Betaine
Glutamic acid
Phenylalanine		Non-essential amino acid
Non-essential amino acid
Non-proteinogenic amino acid
Non-essential amino acid
Essential amino acid		All < 0.01
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Montgomery, E.M.; Cannon, B.L.; Nomura, M.; Leme, R.B.; Forster, I.P.; Pearce, C.M. You Are What You Eat: California Sea Cucumbers Become “Fishier” After Integrated Multi-Trophic Aquaculture with Chinook Salmon. Fishes 2025, 10, 154. https://doi.org/10.3390/fishes10040154

AMA Style

Montgomery EM, Cannon BL, Nomura M, Leme RB, Forster IP, Pearce CM. You Are What You Eat: California Sea Cucumbers Become “Fishier” After Integrated Multi-Trophic Aquaculture with Chinook Salmon. Fishes. 2025; 10(4):154. https://doi.org/10.3390/fishes10040154

Chicago/Turabian Style

Montgomery, Emaline M., Barb L. Cannon, Miki Nomura, Rodrigo B. Leme, Ian P. Forster, and Christopher M. Pearce. 2025. "You Are What You Eat: California Sea Cucumbers Become “Fishier” After Integrated Multi-Trophic Aquaculture with Chinook Salmon" Fishes 10, no. 4: 154. https://doi.org/10.3390/fishes10040154

APA Style

Montgomery, E. M., Cannon, B. L., Nomura, M., Leme, R. B., Forster, I. P., & Pearce, C. M. (2025). You Are What You Eat: California Sea Cucumbers Become “Fishier” After Integrated Multi-Trophic Aquaculture with Chinook Salmon. Fishes, 10(4), 154. https://doi.org/10.3390/fishes10040154

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