A fp7 Project: Management and Monitoring of Deep-sea Fisheries and Stocks wp2 – Template for Case Study Reports Case study 2 demersal deep-water mixed fishery Pascal Lorance, Ifremer, Nantes (coord.)
Section 7.Key uncertainties about the biology, data and management; other issues relevant to DEEPFISHMAN
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- 7.1.Needs for further research
- 7.1.2.Survivals of discarded sharks
- 7.1.3.Selective gear/devices
- References
Section 7.Key uncertainties about the biology, data and management; other issues relevant to DEEPFISHMANSection 7: Please review the key uncertainties about the biology, data and management for your stock and any other issues relevant to DEEPFISHMAN It is then essential that catch and effort data from this fleet are available for stock assessment purposes. The data required are total catch in tonnes, total effort, geographical distribution of the catch and effort (catch and effort by ICES statistical rectangles). Sampling data from this fleet, as required by council regulation (EC) No 2347/2002 of 16 December 2002 establishing specific access requirements and associated conditions applicable to fishing for deepsea stocks should also e made available. 7.1.Needs for further research7.1.1.Stock identityThere are needs in stcok identity some are being addressed by genetic work, nevertheless genetic is not the only way to address stock identity, other options are for example, analyses of trends in abundance, CPUE, yearly and seasonal variations in length, seasonal variations of abundance. These latter method could be used for blue ling and greater forkbeard. For blue ling high number of juveniles are only observed in Icelandic waters, where small juveniles (below 20 cm) probably one year old occur at the coast and individual of 20-60 cm are caught in both commercial fisheries and surveys. Some juveniles are also reported in Faerose surveys but densities seem to be low compared to the adult stock size in ICES Division Vb and XIIb and Subareas VI and VII. Over recent years, there was apparently concommittant increases in blue ling abundance indices from both the fishery and survey in Icelandic waters (Va) and in ICES Division Vb and XIIb and Subareas VI and VII. Greater forkbeard is mainly a by-catch species, total landings are rather small, juveniles occur on the shelf and adult down to 1000 in ICES Division Vb and XIIb and Subareas VI and VII as weel as futher south (Bay of Biscay) and North. The recruitment can be identified in length distributions from surveys. Therefore, survey time-series could be used to assess temporal coherence of recruitment signals. 7.1.2.Survivals of discarded sharksIn 2010, the landings of a minor by-cath of sharks only was allowed. From 2011, no landings will be allowed so that all deep-water sharks will be discarded. This implies an economic loss for the fishery but the ecological benefit is unknown. Some benefit might come from the incentive to avoid areas where sharks form a high proportion of the catch. nevertheless, because they are rarely the dominant species and have moderate market value, sharks have been mainly caught as a by-catch. A high proportion of this by-catch might continue. Based upon visual observation of the conditions of deep-water catch, it has been considered that the survival of deep-water fish returned at sea should be considered zero(Koslow et al. 2000). This may not fully apply to sharks which tend to be brought on-board alive and not apparently damaged. The survival of sharks returned to sea quicky after capture is unknown. Several traumas may occur, including by exposing eyes of deep-water animals adapted to low light level to the sunlight (it could be for exmple that only sharks brought to the surface at night time will survive). Nevertheless, the survival of sharks returned at sea might worth studying. Options for tag-recapture could be considered. One possibility could be to have sharks tagged by commercial vessels with marks allowing to confirming the stay at depth. Because high numbers of marks might be necessary, electronic system might be too expensive and this option requires some technical review. 7.1.3.Selective gear/devicesAnother option for sharks would be to avoid their capture by selective devices. Because some species of sharks are larger than the main target species (blue ling, roundnose grenadier and black scabbardfish) and they have a different behaviour (Lorance and Trenkel 2006) a sorting device could be efficient. No developpement has been done so far but starting from device used to exclude dophins, turtles and large pelagic sharks the definition of a sorting grid and the intallation in commercial trawls could be considered. This could be the best option to reduce the fishing mortality of sharks but it strongly depend upon the sufficient difference in size and behaviour in the trawl between sharks and other species. Most probably it can only be efficient for the larger species (Centrophorus squamosus, Centrocymnus coelolepis, Deania calcea and Dalatias licha) as other species (Apristurus spp., Centroselachus crepidater, Centroscyllium fabricii, Etmopterus spp.) are probably to close to size of target species to be efficiently selected. Netherless, because larger species might be the most long-lived and vulnerable to overfishing, selectivity trials seem appropriate. For sharks, it is unlikely that significant damages due to abrasion if the fishing gears occur. ReferencesICES, 2007a. Report of the working group on biology and assessment of deep-sea fisheries resources (WGDEEP), 8-15 May 2007, Copenhagen, Denmark. International Council for the Exploration of the Sea (ICES), Copenhagen ICES CM 2007/ACFM:20, 478 pp. Ices, 2007b. Report of the workshop on age reading of roundnose grenadier (WKARRG). International Council for the Exploration of the Sea (ICES), 4-6 September 2007, Boulogne-sur-mer, France ICES CM 2007/ACFM:36 Ref. RMC and PGCCDBS, 31 pp. ICES, (2008). Report of the working group on biology and assessment of deep-sea fisheries resources (WGDEEP), 3-10 March 20008, Copenhagen, Denmark, Copenhagen, ICES CM 2008/ACOM:14, 478 pp Knutsen H., Jorde, P.E., Skogen, M., Stenseth, N.C., 2009. Large-scale population structure in roundnose grenadier. ICES international Symposium, Issues confronting the deep oceans: the economic, scientific, and governance challenges and opportunities of working in the deepsea, Horta, Azores, Portugal, April 27-30 2009. Lorance, P., Large, P.A., Bergstad, O.A., Gordon, J.D.M., 2008. Grenadiers of the NE Atlantic - distribution, biology, fisheries and their impacts, and developments in stock assessment and management. Grenadiers of the world oceans: biology,stock assessment and fisheries, Bethesda, MS, USA, 365-397. Pajuelo, J.G., Gonzalez, J.A., Santana, J.I., Lorenzo, J.M., Garcia-Mederos, A., Tuset, V., 2008. Biological parameters of the bathyal fish black scabbardfish (Aphanopus carbo Lowe, 1839) off the Canary Islands, Central-east Atlantic. Fish. Res., 92, 2-3, 140-147. Quéro, J.-C., Porché, P., Vayne, J.J., 2003. Guide des poissons de l'Atlantique européen, identifier 955 espèces. Les guides du naturaliste, Delachaux et Niestlé, Lonay (Suisse), Paris, 465, pp. Appendix 1: overview of available observer data for the French deep-water fishing fleet Directory: lib -> exe exe -> Homework Problem Set 3 Solution I. Reading Assignment exe -> System Modeling Assessment & Roadmap wg exe -> Artemis-2011-1 decision and platform support for model‐based eVolutionary development of Embedded systems Date of preparation exe -> Date: January December 2011 Java 5 Language psm for dds (dds-java) exe -> Notes on bcd by N. Toge (Jan. 5, 2005) Instrumentation and Control General exe -> Case Study 3 Report – Black scabbardfish in ixa exe -> 1 Beneficiaries (Partner Description) exe -> Pre-requisites exe -> Suggested (Sample) Research Project Topics (Fall 2010) Download 2.38 Mb. Share with your friends:
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