Report of the 2017 SPRFMO Workshop of the Squid Working Group Shanghai, China 21 September 2017 1. Welcome and Introduction 1. Dr. Li Gang, nominated as Chairperson of the squid working group during SC4, welcomed participants who introduced themselves to the informal workshop. 2. Administrative Arrangements 2.1. Adoption of Agenda 2. The Working group adopted the agenda provided as Attachment 1. 2.2. Meeting documents 3. The list of documents covered are provided in Attachment 1. 2.3. Nomination of Rapporteurs 4. Rapporteurs were appointed and include Jim Ianelli, Lee Georgeson, and Brian Langseth. 3. Basic biology 5. The workshop noted that SC5-Doc06 Summary Species Profiles covers jumbo flying squid. 6. Australia requested that request for relevant scientific advice be omitted from the species summary because updating it every year would be administratively burdensome. 7. Peru presented SC5-SQ07 on Distribution, size composition, possible stock structure and the assessment of jumbo flying squid (Dosidicus gigas) off Peru by Juan Arguelles, Jorge Csirke, Luis Mariategui, Ramiro Castillo and Ricardo Tafur, summarized as follows. Recent studies provide some insights into the slight differences in the age or size of sexual maturity and the main distribution areas of jumbo flying squid (Dosidicus gigas) which suggests that there are least three strains, groups or population subunits of this species in the Southeast Pacific, and information is provided that shows that all three groups are or have been present off Peru. The extended distribution and wide extension of the fishing grounds poses serious challenges for assessment and the management of fisheries. They proposed that the SC continue to pursue assessment methods that can best be applied within the Convention area. They discussed pros and cons for acoustic survey approaches and on indirect methods such as surplus production for modelling jumbo flying squid. They noted that the assumptions for surplus production methods are likely violated and is cause for concern. Research needs were highlighted and recommended with emphasis on timely implementation by the SC. 8. The working group discussed the biology of squid in terms of the location of spawning grounds and movement characteristics and how this might relate to stock structure off Peru and in the high seas more generally. This has obvious implications for stock assessment. They noted that paralarvae have been found along the whole Peruvian coast, and that no pattern is present to suggest a single spawning area within Peruvian jurisdictional waters. There is evidence to suggest some inshore/offshore movement, but general thought is that there is some east-west segregation by size, with larger squid predominantly inshore and smaller squid predominating in oceanic waters. There is also no strong evidence for large north-south migrations.
9. There is still a lack of understanding around stock structure, but there are indications that there are two to three stocks off the coast of Peru distinguishable by their size at sexual maturity; small sized, medium sized, and large sized at maturity, that straddle the Peru EEZ/high seas boundary. There was some discussion that the change in size could be explained by environmental variables such as temperature. It was suggested that stock(s) in the convention area are probably more so the small and/or medium sized at maturity stocks, because large squid are associated with cold water, which would be related to upwelling along the coasts. However, differences in size of catch may be due to selectivity. Large squid can be caught in the high seas, and Chinese vessels rarely catch the large squid because they are difficult to pull up and are a risk for breaking the line. It was discussed that there was a need to look at the spatial distribution of total catches before 1999 and spatial distribution of length and sexual maturity for the whole period to better inform any inferences around stock structure. Altogether, the discussion highlighted the need to understand fisher behaviour and general fishery characterisation before making conclusions around the use of size structure and sexual maturity information to delineate stock structure. 10. There was also general agreement among working group members that improved collaborations among members is important. Something to help for future research would be to have maturity sampling throughout the year, and to focus on females as they have more clearly defined time period of maturity than males. 11. China presented paper SC5-SQ05 titled Sexual niche partitioning of jumbo squids in the Southeast Pacific Ocean by Yunkai Li, Yi Gong, Xinjun Chen, Yong Chen. In summary, the trophic ecology of the jumbo flying squid using the stable isotope values in the gladii, characterizing the sexual segregation in trophic niche partitioning and morphology of feeding structures during ontogenesis and identifying how females and males coexist during most of their life cycle, possibly due to size dimorphism in feeding structures and sexual differences in energy allocation. Evidence suggests that these two mechanisms likely reduce intraspecific competition, and promote ontogeny of sexual niche partitioning. 12. It was noted that samples were not of the largest individuals. Clarification was sought about the high female to male sex ratio in the samples, and it was acknowledged that it could reflect a real underlying sex ratio in the population, but it could be due to other reasons, e.g. possible difference in behaviour between sexes, such as aggression towards hooks. Concern was expressed that figure 3 was based on few individuals in a single year and therefore may not reflect the population on a whole. The working group discussed that Peruvian samples could be provided to assist this work. 13. There were no recommendations arising from this paper. 4. Abundance, distribution and their relations with the environment 14. China presented SC5-SQ06 titled Impacts of Climate variability on habitat suitability of jumbo flying squid in the Southeast Pacific Ocean off Peruvian waters by Wei Yu, Xinjun Chen, Yong Chen. In summary, the study shows that the climate variability impacts habitat suitability of jumbo flying squid in the Southeast Pacific Ocean off Peru. The El Nino and La Nina event as well as regional environmental conditions had significant influences on habitat quality and distribution of jumbo flying squid and the latitudinal location of suitable habitat was likely to determine the squid distributions. Both suitable habitat areas and catches of D. gigas increased in La Niña years and decreased in El Niño years. 15. There was a question about why El Nino 1+2 index was not used, which is best used for areas nearer the coast. Presenter stated that index 3.4 is better suited for determining influence of environmental variables and therefore best for this study. The working group discussed various effects of El Nino on catches. El Nino may increase catch due to restricting suitable habitat so that catchability increases, but effects on downwelling, and therefore overall productivity, also would 2
occur that and likely override any possible increases in catch. The working group noted though that the data for the presentation were for a few years only. It would be interesting to see if Peruvian EEZ catch would show similar patterns, as Peruvian catch was not used in this analysis. It was discussed that research into climate variability will help to refine assumptions used in stock assessments and that this research should continue to be developed and refined. 16. There were no recommendations arising from this paper. 5. Population structure 17. China presented SC5-SQ03 titled Spatial difference in elemental signatures within early ontogenetic statolith for identifying Jumbo flying squid natal origins by Bilin Liu, Xinjun Chen, Gang Li. In summary the paper covers a study identifying Jumbo flying squid natal origins using early ontogenetic elemental signatures in statolith. Elemental signatures in embryonic statoliths were considered to be a better natural tag than those in paralarval statoliths, although both of them could be used as a proxy for distinguishing different groups. The paralarvae of the same populations followed different dispersal trajectories, which might be responsible for their differences. The paper suggests that the northern (Costa Rica) and southern (Peru and Chile) group potentially have different natal origins and migration patterns. The northern population was putative spawning adjacent to the Costa Rica Dome, and the special Equatorial Counter Current meant that the paralarvae remained in the spawning ground for food. In contrast, the southern population might spawn in the coastal waters off northern Peru, and the paralarvae would be carried northward rather than stay at the birth place for nursery. Overall, the jumbo squid life cycle, especially at early ontogeny stage, is susceptible to variation of oceanography, particularly the ENSO. 18. The working group asked whether the single outlier from the Peru group on Figure 2 was from the single large (989 mm) individual caught in Peru; it was not. The SWG discussed a potential inconsistency in the results around spawning locations, which didn t appear to match up with findings of other research. The results suggest that squid might be swimming against the current to travel towards the southern areas of Peru, although larval dispersal with the current should mean that the squid go northwards. It was clarified, that the pattern of movement from the nursery would be via drift, yet adults could actively move. It was also clarified that other areas can exist, the suggested nursery is not the only one. 19. This presentation sparked general discussion on spawning. There is evidence of extended spawning of D. gigas within Peruvian jurisdictional waters based on survey samples of early life history stages covering this region. Equivalent information is unavailable for the Convention area. The group discussed spawning periods and Peruvian data from their zone showed D. gigas maturing at small and mid-sizes in August, November and in November to January in females. Given limited sampling in the convention area, and evidence of clear seasonal patterns in Peruvian waters (where sampling occurs year round) The group recommended that a comprehensive sampling program be pursued in the SPRFMO the SPRFMO area. 20. There was also discussion on how much length at maturity indicates separate stocks. It was noted that there could be slow growing individuals from the same stock that are small because they are in areas with low productivity due to food limitations, and not actually be a separate stock. Hence length frequencies may not necessarily define stock structure by themselves. A genetic study could assess stock structure although it was noted that given squid biology, there be sufficient sharing of genetic material such that a genetic analysis may not be able to distinguish among stocks even if they exist. 21. The working group therefore recommended that more maturity information be obtained in as many months of the year as possible, and be from the convention area (to supplement 3
4 4 th SC workshop on Squid information available from elsewhere). This is needed to cover the period(s) where maturity is expected. 22. China presented SC5-SQ04 titled Morphological variation and stock classification of Jumbo flying squid based on the statolith shape using wavelet analysis by Zhou Fang, Xinjun Chen, Hang Su, Yong Chen. In summary, the stock classification of D. gigas was evaluated based on the statolith shape in this study. The statolith shape of CH stock had the largest size and CR stock had the smallest size within the shape indices and all the shape indices had significant differences among stocks. Statolith shapes from different geographic stocks were reconstructed by wavelet coefficients derived from the statolith images via computer software, and stock classification was performed. The results showed that reconstructed statolith shapes could realistically reflect the stock morphological difference, which was mainly observed in the rostrum and wing sections of statoliths. Machine learning methods were also used for stock classification in this study and produced a superior classification to traditional methods. This study supports the conclusions of previous studies that two separate stocks of D. gigas exist in the ETP. Physical oceanography and feeding behaviour are the two main causes of statolith shape variation among stocks. This study further reinforces the idea that analysis of statolith shape, using techniques such as RF and SVM, is a useful tool for stock recognition. 23. There was no discussion on this presentation. 6. Stock assessment 24. Craig Loveridge presented SC5-SQ01 covering the data reported on squid catch to SPRFMO secretariat. 25. The working group discussed whether the catch figures presented were likely to be a reliable estimate of total catch. The Secretariat stated that there was apart from the little information from the Ecuador EEZ (there are records of catch as indicated by national reports but specific values for catch have been submitted), the catch series should be reasonably complete. There is some more work to do on checking some of the earlier data to remove potentially duplicated catches within some years. 26. There were no recommendations arising from this paper. 27. China presented SC5-SQ02 A stock assessment of the jumbo flying squid (Dosidicus gigas) in Southeast Pacific Ocean (2017) by Luoliang Xu, Bai Li, Gang Li, Xinjun Chen, Yong Chen. In summary, the jumbo squid stock in the Southeast Pacific is not overfished and overfishing does not occur. The current catch level is much lower than the estimated MSY and is sustainable. CPUE data from Chinese vessels may be a good proxy for stock abundance outside the jurisdictional water of other fishing entities. The stock assessment model could be highly facilitated if the CPUE data or any other survey data within the jurisdictional water of other fishing entities are included. This study simplified the complex population structure. More sophisticated models to include size structure and/or possible meta-structure of the population should be developed. However, this can only be done if we have size composition and/or spatially-explicit catch and abundance index data which may become available if relevant parties work together. Data-limited methods could be another way to make management suggestion. Management strategy evaluation (MSE) could be developed to compare management strategies derived from the stock assessment paradigm and the data-limited method paradigm respectively. The population dynamics of jumbo squid can be significantly influenced by changes in their environment. Critical environmental factors should be taken into consideration to make a short-term management decision for jumbo squid in Southeast Pacific Ocean 28. It was noted that units of catch in this paper were in 10,000s. Concern expressed about amount of contrast in CPUE, which was quite flat, although it was noted that annual variation is about 2 fold
5 4 th SC workshop on Squid so could provide sufficient contrast to estimate parameters. Another concern was that the model used the Chinese only index starting in 2003, and that the Chinese catchability may increase in the first few years as the fleet learns about the area being fished. Discussion occurred about the stock definition for squid. It was agreed that stock structure is an important matter to address for use in models. It was also discussed that careful consideration of the modelling approach be done and that adoption of a model not be done just because it is cheap and easy. Future assessment work could include incorporating changes in catchability, incorporating catches back to 1991, and including other countries indices if available. There was also discussion about doing a high seas only model although there was not agreement about whether this would be necessary. 29. This presentation sparked discussion in general about stock definitions and data needs. 30. The working group noted that it was important to determine how many stocks are being dealt with, or the outputs of the surplus production model or any other model will be less useful. There is a risk that the MSY estimates from this surplus production model, could potentially result in stocks or subpopulations being overfished or subject to overfishing if indeed multiple stocks exist. It was noted that the economic importance of the squid fishery should necessitate that this additional work on stock structuring is undertaken. The working group agreed that it is important to carefully consider the modelling approach used, and to enhance research on stock structure, spawning grounds, and other basic biology (i.e. maturity). 31. Korea presented SC5-SQ09 titled Observer report on Jumbo flying squid jigging fishery in the SPRFMO Area by S-G. Choi, J-H. Lee, S. Shin, Y. Lee, E. Kim, S Chung, JB. Lee & D. An. The aim of this survey is to collect basic information on the sustainable use of fisheries resources in the South Pacific and on the impacts of fishing on the marine ecosystem. A scientific observer was on board a jigging vessel which targets jumbo flying squids in the SPRFMO Convention Area to conduct the survey. A total of 3,281 jumbo flying squids were measured for biological observations. Mantle length frequency ranged from 50 to 110 cm. The dominant stage of maturity observed for both male and female jumbo flying squids was gravid. Stomach contents of sampled jumbo flying squids contained only its cohorts. Fishing depth was from 50 to 175m, and the range of surface water temperature at fishing ground was 18-19.9. The weather of 26 days was fair while 49 days was cloudy. Korea is planning to strengthen its efforts to conduct research on the composition of the ecosystem including the target and by-catch species, sea birds, and marine mammals by maintaining its interest in jigging surveys and dispatching observers on jigging vessels. 32. There was a question about seabirds by the working group. The presenters confirmed that there was no entanglement by seabirds in the observed Korea squid jigging activity, nor was there any bycatch of seabirds. It was noted that Korea uses automatic jigging which would explain the presence of very large individuals as recorded by the observer. The information presented can be used to assist in building a standardized form for reporting observer information. 7. Approaches to coordinating research 33. China presented paper SC5-SQ08 on Proposals on research programme and data sharing for Jumbo flying squid in Southeast Pacific. This paper proposed the following areas: Develop data sharing and collection mechanism Develop biological research programme for jumbo flying squid Stock assessment model development 34. The workshop discussed data sharing within the mandate of existing commission protocols and which members would be most likely to have data to share. 35. It was noted that the working group cannot ask the SC or Commission to go beyond the mandate of the Convention in terms of work within the SPRFMO Area and work within EEZs. Also, it was noted that because there isn t a squid fishing measure, the amount of data to collect is not
specified. Therefore, it was reiterated that observer templates for squid jigging operations were needed and that these should be developed as soon as practicable. The Secretariat stated that the recent squid information provided for 2016 for the Convention area is much better resolution thanks to the use of templates that the SC developed since SC4. The group also reiterated their desire to comply with past recommendations to recover historical data and report the historical information using the new detailed reporting forms. In relation to point 3 of the proposal, it was noted that past work on model comparisons has been done. It was suggested that this previous work be used to inform appropriate model approaches and that the group avoid reproducing analyses done in the past. 36. Chile noted that the proposed framework is an interesting mechanism to collect, share and analyse data, and indicated its eagerness to cooperate fully with the three-research branches. Chile believes the main goals should be to clarify issues relative to numbers of stocks inhabiting the Southeast Pacific region, improve the certainty of life history parameters, and agree on a stock assessment framework according with the data available. Therefore, Chile encourages others members to improve the on-board sampling monitoring of jumbo squid within waters covered by the Commission, and coordinate an inter-sessional research working plan. 8. Recommendations to SC05 37. The squid working group made the following recommendations to SC05: 1. Acknowledge that Jumbo flying squid distributed in the Southeast Pacific straddles between the Convention area and the adjacent areas under national jurisdictions. 2. Evaluate working hypotheses on stock structure using data combined from members and CNCPs. 3. Also relative to stock structure, research on the distribution, migration routes and intermixing patterns, should be pursued (e.g., samples for micro-constituents, genetics, morphometrics, tagging, etc.). This should include mature male and female length frequency distribution comparisons at fine temporal and spatial scales. 4. Promote research on the reproductive process and the effect of environmental factors in determining the timing and the location and extension of spawning areas. 5. Determine the most suitable stock assessment models and management alternatives to be applied for jumbo flying squid for use in the Convention area. This could include research on methods for recruitment and escapement estimation. 6. Promote research on fishing impacts relative to predator-prey interactions and cascading ecosystem impacts and changes in life history parameters including possible effects of changing environmental conditions. 7. Refine and develop data templates to address data gaps for informing a full stock assessment, as not all required information is contained within the templates. 8. Encourage members and CNCPs to share data and information necessary for stock assessment. 9. Use current detailed reporting forms to recover historical data and report the historical information to the extent possible. 10. Develop an appropriate mechanism to achieve these objectives 9. Adoption of Report & Meeting Closure 38. The workshop concluded at 17:30 and the workshop agreed that the draft report will be presented and finalized during SC05 for consideration. 6
Attachment 1. Agenda of the squid working group 1. Welcome and Introduction... 1 2. Administrative Arrangements... 1 2.1. Adoption of Agenda... 1 2.2. Meeting documents... 1 2.3. Nomination of Rapporteurs... 1 3. Basic biology... 1 4. Abundance, distribution and their relations with the environment... 2 5. Population structure... 3 6. Stock assessment... 4 7. Approaches to coordinating research... 5 8. Recommendations to SC05... 6 9. Adoption of Report & Meeting Closure... 6 7
Attachment 2. Workshop documents 8