Evidence of Non-Random Social Interactions between Pairs of Bait-Attracted White Sharks in Gansbaai (South Africa)
, Francesca Romana Reinero 1, Riccardo D’Agnese 1, Antonio Pacifico 1,3, Gianni Giglio 4 and Emilio Sperone 4
Round 1
Reviewer 1 Report
This manuscript used ten-year observation and video data to examine the non-random social interactions in the surface behavior of bait-attracted White Shark in Gansbaai, South Africa, between March and May in 2009–2018. The paper is interesting and potentially useful, as it identified 525 surface-generated social interactions of White Shark in the study area and classified them into eight social-interaction patterns, and made an attempt to suggest that non-random social interactions occurred when pairs of White Shark approached the passive surface bait and the species showed a dominance hierarchy during the study period. I think that the long-term observation of multiple social-interaction patterns in a top predator fish species, which is characterized by a high ratio of brain to body mass and has been observed to develop and maintain complex social behavior, in a video recording framework is an interesting advantage of this paper in relation to others that deal with similar topics. There are some justifications the authors need to include, which will enrich the content of the research while clarifying the selection and implementation of the approaches used. The specific comments are:
Abstract
- (1) Page 1 Line 16. “surface baits” to “surface bait”.
- (2) Page 1 Line 20. “splash fights, piggybacking” to “splash fights, and piggybacking”.
- (3) Page 1 Line 21. “the surface passive bait” to “the passive surface bait”.
- (4) Page 1 Line 22. “during ten years of data collection” to “during the ten years of data collection”.
Introduction
- (5) Page 2 Line 53 (and others throughout the manuscript). “scalloped hammerhead sharks” to “Scalloped Hammerhead Sharks”. I would suggest that the common names of fish species be capitalized, following the usage in the 7th edition of Common and Scientific Names of Fishes from the United States, Canada, and Mexico (AFS Special Publication 34; 2013).
- (6) Page 2 Line 57. “interaction among white sharks” to “interactions among White Sharks”.
- (7) Page 2 Line 57. “has received” to “have received”.
- (8) Page 2 Line 69. “population it” to “population, it”.
- (9) Page 2 Line 69. “specimens of a similar size” to “specimens of similar sizes”.
- (10) Page 2 Line 91. “surface-bait” to “surface bait”.
- (11) Page 2 Line 91. “in the Dyer Island Nature Reserve, ” to “in the Dyer Island Nature Reserve in Gansbaai, South Africa, ”.
- (12) Page 2 Line 92. “such interactions are not” to “such interactions were not”.
- (13) Page 2 Line 92. “choice, aimed at” to “choice, which aimed at”.
- (14) Some additional information such as brief background on the feeding and spawning grounds, life history, potential prey and competitor species of White Shark in Gansbaai, South Africa, which might be related to the social behavior of White Shark that was examined in this study, would be helpful in the Introduction section to set the stage. I would also suggest emphasizing somewhere in the Introduction section the significance of the long-term observation of multiple social-interaction patterns in a top predator fish species, which is characterized by a high ratio of brain to body mass and has been observed to develop and maintain complex social behavior, in a video recording framework, because these approaches might help people from broader field find your work useful rather than people just working on the particular species or area being interested in it.
Materials and Methods
- (15) Page 3 Line 99. “wide and” to “wide, and”.
- (16) Page 3 Line 99. “colonies. Geyser” to “colonies; Geyser”.
- (17) Page 3 Line 100. “180 m wide” to “0.18 km wide”.
- (18) Page 3 Lines 102-104. “which is the meeting point between the Benguela Current, which is the eastern boundary current of the subtropical vortex located in the south Atlantic Ocean, and the Agulhas Current, which is the current forming the western limit of the Indian Ocean” to “which is the meeting point between the Benguela Current (the eastern boundary current of the subtropical vortex located in the south Atlantic Ocean) and the Agulhas Current (the current forming the western limit of the Indian Ocean)”. I would suggest rephrasing this part to avoid repeatedly using subordinate clauses with “which” in one sentence.
- (19) Page 3 Line 127. “were spent” to “was spent”. Time is typically considered as an uncountable noun.
- (20) Page 3 Line 128. “a 12 m long boat” to “a 12-m long boat”.
- (21) Page 3 Line 129. “a 14 m long boat” to “a 14-m long boat”.
- (22) Page 3 Line 129. “A 4 m long, 3 m high, and 2 m deep” to “A 4-m long, 3-m high, and 2-m deep”.
- (23) Page 4 Line 172. “2 min” to “2 minutes”.
- (24) Page 5 Line 177. “verified through” to “through”. I would suggest removing “verified” to avoid repeatedly using the word “verify” in one sentence.
- (25) Page 5 Line 182. “no difference” to “no significant difference”.
- (26) Page 5 Line 183. “a difference” to “a significant difference”.
- (27) Page 5 Line 185. “identical effects” to “similar effects”.
- (28) Page 5 Lines 177-189. There is little explanation as to why chi-square test and Cochran’s Q test were chosen in this study. There have been some other multivariate statistical approaches (e.g., Cochran-Armitage test) that were used in ecology when it comes to analyzing multiple comparisons and the relative contribution of target treatments/variables. However, there is little justification as to why the authors only chose these methods. I would suggest adding in the Methods section a brief explanation to justify why these approaches and not other also commonly used ones were chosen. Given the potential of statistical methods to influence the understanding of relationships between White Shark social behavior and passive surface bait in the study area, it would be better to critically assess why some approaches are chosen and their potential and weaknesses for the available data and specific environment considered.
- (29) Page 5 Lines 177-189. When you used chi-square test and Cochran’s Q test to analyze the relationships between White Shark social behavior and passive surface bait in this study, did you use raw or transformed values from the recorded data to apply the statistical analysis on? It would be better to specify a little more even though data transformation may not be necessary for some situations, because it is an important step to make sure the variables meet the underlying assumptions of the algorithms before conducting any statistical analyses. Statistical approaches with different mechanisms may have different underlying assumptions of normality, linearity or multicollinearity, and some variables may need to be transformed to meet specific assumptions.
Results
- (30) Page 5 Figure 3. Why the numbers of observations in 2017 and 2018 were much lower than those in the other years?
- (31) Page 5 Line 202. “at close range” to “at a close range”.
- (32) Page 6 Line 209. Does “the first” mean the followed shark or the shark that was followed? Please specify that as it is a bit confusing here.
- (33) Page 6 Lines 209-217. I would suggest specifying a bit more about the main difference between “Follow / give way” and “Follow”.
- (34) Page 6 Lines 229-230. “a male and female shark of” to “a male and a female sharks of”.
- (35) Page 8 Line 240. “Tab. 1” to “Table 1”.
- (36) Page 8 Line 248. “with degrees of freedom” to “with the degrees of freedom”.
- (37) Page 8 Line 250. “Tab. 2” to “Table 2”.
- (38) Page 8 Line 251. “no difference” to “no significant difference”.
- (39) Page 8 Line 252. “a difference” to “a significant difference”.
- (40) Page 9 Lines 257-258. “4. Discussion” should be removed here.
Discussion
- (41) The entire Discussion section was put in one single paragraph. Please rearrange the information in this section and divide it into different paragraphs.
- (42) Page 9 Line 274. Do you have any references supporting the “reproduction”?
- (43) Page 9 Line 286. “2009b): ” to “2009b); ”.
- (44) Page 9 Line 290. “study social interactions” to “study their social interactions”.
- (45) Page 9 Line 296. “2000): ” to “2000); ”.
- (46) Page 10 Line 348. “Follow-give way” to “Follow / give way”. Please keep the name of this social behavior consistent throughout the manuscript.
- (47) Page 10 Line 353. “argue” to “argued”. Please keep the tense consistent.
- (48) Page 11 Line 361. “adults: ” to “adults; ”.
- (49) Page 11 Line 361. Does “in this area” mean the study area in your work or the study area in Lisney et al. (2007)? Please specify that as it is a bit confusing here.
- (50) Page 11 Line 368. Please add references for the studies on “Neptune Islands in Australia” and on “Southern California”.
- (51) Besides the passive surface bait that was examined in this study, the observed social behavior of White Shark may also be affected by potential factors such as abiotic conditions, natural prey and competitor species, and interspecific interactions. I would suggest acknowledging in the Discussion section these additional factors based on literature and their potential influence on the social-interaction patterns of White Shark in the study area.
Tables and Figures
- (52) Page 3 Figure 1 Line 117. “Map of Dyer Island’s Nature Reserve” to “Map of Dyer Island’s Nature Reserve in Gansbaai, South Africa (34°41’ S; 19°24’ E)”.
- (53) Page 4 Figure 2 Line 175. “the 14 m long boat” to “the 14-m long boat”.
- (54) Page 8 Figure 5 Line 237. “Percentage frequencies social behavior modules” to “Percentage frequencies of social behavior modules”.
- (55) Page 8 Figure 5. There should be an additional bar for “Piggybacking”, even though this social behavior was observed only once.
- (56) Page 8 Table 1 Line 245. I would suggest adding in the table caption a brief description of this table and what the values stand for. A good table or figure caption should make the table or figure understandable without reference to the main text.
Author Response
Dear Referee,
please see the attachment
Best regards
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The work under review is devoted to current interest topic – the sociality in sharks. While the various forms of social behavior in bony fish have been fairly well studied and still studied quite active, for cartilaginous fish, for sharks in particular, there are more questions than answers. The present work fills this vacuum to some extent using the white shark as an example. The text is well written. Nice drawings, especially drawing #4. The authors found and use a lot of data from the literature to analyze their results.
But I have a few wishes to improve the text of the article.
1. The article does not always clearly define the boundary (separation) between sharks in general and the white shark in particular. Sometimes it is difficult to understand who specifically the authors have in mind - all sharks or just the species under study? For example, lines 16-18, 191-192, the caption for figure No. 3 and in other places. This should be corrected and well defined.
2. The authors write that they individually recognized the observed white sharks (lines 148-152). But it remains a mystery to me - for what purpose was this done? I did not find anything in the text where the results of using such individual fish recognition were presented.
3. I am not at all satisfied with tables No. 1 and No. 2. To be honest, I doubt their necessity, the essence of these tables is easier to express in a short sentence. Well, in the current form, these tables cannot be placed in the article, this is absolutely certain.
4. Very large paragraphs look strange, which makes the text less logical and less structured and makes it difficult to read. This remark concerns the Introduction, and especially sections “2.2. data collection" and "4. Discussion".
Author Response
Dear Referee,
please see the attachment.
Best regards
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have addressed most of the comments. I just have some minor suggestions below, which I hope could help further improve the clarity of the paper.
For the revised version:
- (1) Page 1 Lines 16-24 (and others throughout the manuscript). “white sharks” to “White Sharks”. Some of the common names of fish species were capitalized whereas some were not capitalized in the manuscript. Please make the format consistent throughout the manuscript.
- (2) Page 2 Line 70. “of similar size” to “of similar sizes”.
- (3) Page 6 Line 219. “The reduced number of” to “The reduced numbers of”.
- (4) Page 6 Line 221. “because the presence of a pair of killer whales” to “because of the presence of a pair of Killer Whales”.
- (5) Page 6 Line 233. Does “it” in “causing it to give way” mean the followed shark or the shark that was followed? Please specify that as it is a bit confusing here.
- (6) Page 6 Lines 233-241. I would suggest adding a brief description of the main difference between “Follow / give way” and “Follow”.
- (7) Page 7 Line 255. “shark of” to “sharks of”.
- (8) Page 9 Table 1 and Table 2. The table caption should be put on top of these tables rather than at the bottom.
- (9) Page 9 Line 313. “Tab. 2” to “Table 2”.
- (10) Page 9 Line 325. “degrees of freedom” to “the degrees of freedom”.
- (11) Page 9 Line 326. Why is there a symbol of “°” in “Type I° Error”?
- (12) Page 12 Line 440. “in adults: ” to “in adults; ”.
Author Response
Dear Referee 1, second Tour.
Please see the attachment
Author Response File: Author Response.pdf
