Thumbnail Image

2015 ISSF Stock Assessment Workshop “Characterising uncertainty in stock assessment and management advice”







Also available in:
No results found.

Related items

Showing items related by metadata.

  • Thumbnail Image
    Meeting
    Provision of scientific advice for the purpose of the implementation of the EUPOA sharks. Final Report. European Commission, Studies for Carrying out the Common Fisheries Policy (MARE/2010/11 - LOT 2) 2013
    Also available in:
    No results found.

    The scope of the European Union Plan of Action for Sharks covers directed commercial, by-catch commercial, directed recreatiol, and by-catch recreatiol fishing of any chondrichthyans within European Union waters. It also includes any fisheries covered by current and potential agreements and partnerships between the European Union and third countries, as well as fisheries in the high seas and fisheries covered by RFMOs maging or issuing non-binding recommendations outside European Union waters. S cientific advice for the purpose of the magement of shark species in the high seas is carried out mainly via the Scientific Committees of the relevant Regiol Fisheries Magement Organisations (RFMO), as well as through specific projects by tiol institutes, and other research organisms. However, the level of knowledge concerning many shark populations in the high seas of the Atlantic, Indian and Pacific Oceans is far from satisfactory. It is therefore necessary to identify gaps in the current know ledge of fisheries, biology and ecology of sharks that should be filled in order to support advice on sustaible magement of elasmobranches' fisheries and undertaking studies to fill those gaps. Therefore, the objective of this project is to obtain scientific advice for the purpose of implementing the EUPOA on sharks as regards the facilitation of monitoring fisheries and shark stock assessment on a species-specific level in the high seas. The study is focused on major elasmobranch species caught by both artisal and industrial large pelagic fisheries on the High Seas of the Atlantic, Indian and Pacific area, which are currently monitored and potentially maged by respective Tu RFMOs. Specifically, firstly the study aims to collate and estimate historical fisheries data especially on species composition of catches, catches and effort, size frequencies in order to identify the gaps in the current availability of fishery statistics as well current knowledge biology and ecology of sharks tha t should be filled in order to support the scientific advice provided to RFMOs on sustaible magement of elasmobranch fisheries. And secondly, the project aims to review and prioritise the gaps identified to develop a research program to fill those gaps in support for the formulation of scientific advice for magement of sharks. The data and knowledge gaps identified through Phase I will allow focusing and prioritising the future research. From this summarisation of Phase I it will be clear as to what data is available for providing magement advice for shark species, and where gaps in the data render this task difficult. In a second step, recommendations for data collection improvements as well as research necessities and activities will be described. The data collected in Phase I of the project gives a complete picture of the current data availability of information about catch and effort, observer programs, size frequency information, biological information and fishery indicators that may support the assessment of major shark species in Tu RFMOs. In spite of the importance of shark catches by industrial fleets, they have traditiolly consisted of bycatch of commercial fisheries and sharks are most often discarded or finned. Therefore, most of the times, shark catches are not recorded, especially with the required level of resolution, and catches must be estimated by statistical procedures based on observer data, fishing effort and different covariates. Moreover, the informatio n recorded is not usually RFMO) databases. The information on shark bycatch is scarce and their estimates found in the literature are not homogenous which made the raising and/or estimates of ratios (by-catch/target catch) uncertain due to various assumptions made (e.g. conversion of the estimates in number of individuals into weight without any information on the mean size per species). In summary, the main difficulties and data gaps identified in the project can be described as follows: there is a lack of shark reporting in artisal and coastal fisheries; there is a lack of shark reporting in industrial fisheries and when is reported usually is not broken down by species; there is a lack of any size frequency data; there is a lack of regiol biological/ecological information for sharks; there are difficulties to access to the data both at RFMO level and at a country level; species misidentification which affect the collection of fishery statistics; low observer coverage for most of the fleets/areas; difficulties with the use of logbook data for shark assessment (misidentification, underreporting, change in targeting practice). The work carried out in first phase of the project focuses on the collection of fishery information publicly available, mainly in the website public domain of the RFMOs in the Indian, Pacific and Atlantic Ocean as well as in the Mediterranean Sea (ICCAT- GFCM, IOTC, IATTC, and WCPFC) but also on information available in the literature, most of which com es from documents presented at the scientific meetings or workshops of RFMOs. The RFMO data administrators were also contacted in order to obtain any additiol fishery statistics data. Similarly, information from flag states, and from EU- member states, was requested in order to improve the information available on discards levels, size frequencies and biological information. Apart from RFMO official statistics, and in order to get more accurate and altertive catch data, shark catch estimations f or the most recent period were appraised based on fleet specific ratios of shark catch over tu (or target) catches. This was done in a two step process, first a general ratio between shark catches over tu (target) catch was applied to estimate total shark catches for major fisheries and, then, the relative proportion by species in the catch was applied to estimate shark catches by species. Those ratios were obtained from the literature search and/or data from observer programs available in the R FMO or in the literature. This exercise allows identifying the fleets that could be mainly responsible for the catch of the main shark species included in the study based on the best assumption of the shark catch over target species catch ratios derived from the literature but also allows identifying the main impacted shark specis by fisheries in each areas as well as the main origin of underreporting. In the Atlantic and Pacific (east and west), the Longline fleet targeting sharks, swordfish an d/or tropical tus is the most important métier catching sharks; which contributes with 59 %, 86 % and 95 % to the total shark catches respectively. On the contrary, the picture in the Indian Ocean is different where gillnet (GN - sensu lato) are contributing with 61 % of the total shark catch in comparison to 18 % for longliners. In general, the species composition of the sharks in different métiers is similar in all Oceans as well as in the Mediterran Sea. For example, Longline (LL - sensu lato ) impacts mainly blueshark and shortfin mako and in a minor extend hammerhead, thresher, silky and oceanic whitetip sharks; whereas Gillnet (GN - sensu lato) are impacting mainly silky, thresher, Oceanic whitetip, and shortfin mako sharks. The catch of silky and oceanic whitetip shark for the longline fleet in the West Pacific is higher than other longline fleets of other Oceans because they are operating in more equatorial waters. Although, in all the Oceans, the contribution to the total catch of Purse seines is minor (maximum of 5 % of total catch in the West Pacific); the species composition of purse seines catch is clearly domited by silky and oceanic whitetip sharks. In all Oceans the main species impacted is blueshark with around 65-75 %, with the exception of the Indian Ocean and Mediterranean Sea, of the total shark catch. The contribution of the rest of the species can vary depending on the relative contribution of different fleets as well as the spatial distribution of the d ifferent fleets. However, in general the blueshark catch is then followed by shortfin mako, hammerhead, silky, thresher, Oceanic withetip shark. In the Indian Ocean, the blueshark contribution to total shark catch is around 35 % followed by silky shark (21 %), thresher (16 %), Oceanic whitetip (11 %), shortfin mako (10 %) and hammerheads (6 %). And in the Mediterrenean, blueshark contribution is around 50 % while other species make up the rest: thresher sharks (25 %), mako sharks (13.3 %), tope shark (6.1 %), rays (3.5 %), and porbeagle (1 %). The comparison between the declared value and the estimated value can be considered as a figure for undereporting. For example, it is worth mentioning that the total average amount of the investigated species estimated is 1.5, 13 and 7 times higher than the average amount declared in the Atlantic Ocean, Mediterranean Sea and Indian Ocean, respectively. However, as the estimation carried out in this alysis was based on ratio of shark catch over to tal target catch there is high uncertainty on fil estimations coming from different sources; such as métier classification, from target species quantities declared and from the shark/target catch ratio used to estimate the shark species investigated; which recommend to take these estimations with caution. It was not possible to apply this methodology to the Eastern and Western Pacific due to the lack of access to disaggretate tu/target species catches from the IATTC/WCPFC public databases. And t he data above should be considered in the light of the different species productivity and susceptibility of a given species to a giving métier. This is important to take into account because in some cases a minor catch of one species from all fleets, or one fleet in particular, can have a great impact if the species in question is more vulnerable showing low productivity and high susceptibility to the fleet(s). So, it is important to consider the results above in the framework of Ecological Risk Assessment (ERA) which can help to identify priorities for observer programs/research efforts. Filly, data gaps identified in relation to shark fishery statistics have been summarized with the aim to develop a research framework that would allow filling those gaps in order to assess and mage the shark population worldwide in a sustaible manner. The design of such programme is benefited and integrates all the information collected through phase I. For example, the data and knowledge gaps identif ied and listed/inventoried through Phase I allows focusing and prioritised the future research. From this summarisation of Phase I it is clear as to what data is available for providing magement advice for shark species, and where gaps in the data render this task difficult. At this stage, recommendations for data collection improvements as well as research necessities and activities are described. As such, the review of existing information; as well as the identification of information gaps, ma in shark species impacted and main métier responsible for major shark catch; presented above provides the basis for development of a research program and priorities for the assessment of the status of sharks in Tu RFMOs. As it is not possible to develop a research program for all the Tu RFMOs, a general framework to develop the research program in support of the scientific advice for shark magement is proposed; which includes: (1) a research framework to identify the main species and fleets that needs to be prioritized for the collection of fishery data and information in order to assure the assessment of principal shark species regiolly in the Tu RFMOs; (2) a general recommendations for all Tu RFMOs to improve the data collection to fill the gaps identified above; and (3) options for magement and mitigation measures for sharks. The research framework is proposed to be organized in three steps: (i) estimation of shark catches by species using the method proposed here which allows ident ifying the most impacted shark species and the métier most affecting those species; (ii) a prelimiry Ecological Risk Assessment (or other prelimiry assessment based on fishery indicators) by fleets which allows to identify the most vulnerable species to focus the efforts in conjunction with point (i); and (iii) specific recommendations of how to apply possible magement measures, to improve data collection and assessment of those fleets/species identified as priorities based on points (ii) and (i ii). The implementation of the three steps is highly related. The project also recommends actions to fill the identified gaps structured in sections as data collection, data reporting, data resolution, data access, and assessment. As the data collected through phase I give a complete picture of what are the main fleets targeting the more important shark species caught in the Tu RFMOs, both EU and other countries catching shark, as well as the extent of their volume; this exercise also helps to i dentify the different species for which more focus is needed and those that are supposed to be caught in a lesser extent. For example, this helps to focus the target or more important fleets to monitor and design specific representative observer schemes for those fleets as necessary. Having in mine the data gaps for major fisheries impacting pelagic sharks stocks in the different t-RFMOs Conventions areas as well as the most important metier catching sharks and most impacted shark species; the p roject proposes some possible solutions and recommendations for the implementation of observers programmes on those fisheries, aiming to improve shark data collection, mely regarding shark catch and discards: species composition; vessel mortality; size and sex data. Magement measures are essential when a given stock is seriously affected by the fishing activity and are aimed at limiting the impact of this activity. The election of a measure will depend on the stock status, on the behavior of the species, on the species being target or not, etc.; but the project summarizes several options of magement and mitigation measures applicable to shark species.
  • Thumbnail Image
    Meeting
    Report and documentation of the Indian Ocean Tuna Fisheries of Indonesia Albacore Catch Estimation Workshop: Review of Issues and Considerations 2013
    Also available in:
    No results found.

    The Indian Ocean Tu Fisheries of Indonesia Albacore Catch Estimation Workshop was held in Bogor and Jakarta from 21 to 25 June 2013. The workshop was held in response to a request from the DGCF of Indonesia for the IOTC Secretariat to assist the DGCF with a review of catches of albacore in the Indian Ocean, following recommendations by the IOTC Scientific Committee and the Commission to assess the quality of the catches of albacore, in particular those reported by Indonesia. The main objective o f the workshop was to review the catches of albacore derived from data collected from the tu fisheries of Indonesia, and other altertive sources and, where required, produce a new catch series for albacore. During the workshop, invited experts discussed the data collection and data magement systems currently in place in Indonesia, the catches derived from the data collected, and agreed to recommend further actions to improve the estimates of albacore, and other species, in the future. Their disc ussions were informed and stimulated by one document and four presentations that covered a wide range of topics (Page 2). These included: DGCF’s sampling design, implementation, and official estimates of catches of albacore for the period 2002-12; status of implementation of Indonesia’s Vessel Monitoring System and summary of results (2012); status of implementation of Indonesia’s Logbook System and summary of results (2012- 13); exports of tu and tu-like species recorded by the Dis Perikan Prov incial Office in Bali (2002-12); catches of albacore by the fisheries of Indonesia in the IOTC Area (2002-12); catches of albacore by the fisheries of Indonesia in the WCPFC Area (2002-12); and imports of albacore recorded by canning factories cooperating with the Intertiol Seafood Sustaibility Foundation (2009-12). The Workshop concentrated its efforts in reviewing estimates of catch of albacore by vessels flagged in Indonesia, with a view to improve estimates of total catch, and catches by gea r, focusing on the period 2002-11. The new catch series of albacore, as adopted by the Workshop, is presented in Table 5 (Page 9). The Workshop identified various issues concerning the estimation of catches of albacore (page 12), in particular: incomplete reports from the fishing sector; insufficient monitoring of albacore in port, in particular frozen albacore; insufficient logbook coverage and poor quality of data reported on logbooks; insufficient monitoring of activities of Indonesia’s forei gn based fleet; poor species identification and insufficient training and supervision of enumerators; insufficient data magement and validation, in particular due to the fact that data from the districts are processed by hand, not using Indonesia’s centralized database system; and inordite changes in the catches of albacore, and other species, and breakdown by gear, between consecutive years. The Workshop noted that the above issues compromise the quality of estimates of catch of albacore, and o ther species, for the fisheries of Indonesia, and limit Indonesia’s capacity to comply with intertiol data requirements, in particular those agreed by the IOTC. In this regard, the Workshop proposed implementation of a range of actions (page 13) to address the issues identified and recommended that the DGCF make every possible effort to implement those actions, as required. The Workshop noted that the DGCF may require assistance in the implementation of some of the recommendations, and encourage d the continuation of coordited advice and support from the IOTC, the OFCF, WCPFC, SPC, and other governmental and non-governmental organizations, in the strengthening of data collection and processing activities in Indonesia.
  • Thumbnail Image
    Document
    Comprehensive Report IOTC-OFCF Project Phase II (June 2007 ~ March 2010) 2014
    Also available in:
    No results found.

    Since April 2002, in the framework of the IOTC-OFCF Project, the Indian Ocean Tu Commission (IOTC) and the Overseas Fishery Cooperation Foundation of Japan (OFCF) have been devoting a considerable amount of time and resources to enhancing data collection and processing systems for tu fisheries in the developing countries of the IOTC region. For this purpose, the Project initiated a broad range of activities involving cooperation with institutions in the recipient countries, including:   strength ening of data collection through extension of field activities; capacity-building activities in the areas of data collection and magement, including database support; documentation of fisheries in the IOTC region; and recovery of historical data on fisheries targeting tu or tu-like species. Phase I of the Project was implemented during five years, from April 2002 to March 2007. The activities initiated during Phase I contributed substantially to improving the quality of the data in the IOTC data bases, in particular the quality of nomil catches and size-frequency data for the fleets involved. Following the success of Phase I of the Project, the OFCF agreed to support the implementation of a new phase which would extend the activities of the Project for a maximum of three years, from 2007 to 2010. The present report covers the activities of the IOTC-OFCF Project during Phase II, and also includes an overview of the activities implemented through Phase I and the current status of implemen tation of the recommendations issuing from those activities. The following activities were implemented by the Project during Phase II: Comoros: The Project sent a mission to assess the status of data collection in that country. Indonesia: The Project provided equipment and materials for enhancing effort data collection for the Indonesian fresh tu longline vessels. A workshop on the Indonesia logbook programme was held in May 2009, with the collaboration of the Indonesian Directorate General of C apture Fisheries and other tiol and intertiol organizations, including the Western and Central Pacific Fisheries Commission (WCPFC) and the Commission for the Conservation of Southern Bluefin Tu (CCSBT), in order to assist in initiating Indonesia’s own programme. Kenya: The Project carried out verification of the data collected from the sport fisheries of Kenya that were compiled during Phase I of the Project. Mauritius: The Project sent a mission to assess the importance of foreign fresh-tu lon gline fisheries in the Southwest Indian Ocean region. Oman: Sampling programmes were carried out in Oman for collecting size data for three species caught by the artisal fisheries in the Arabian Sea from January 2009 to December 2009. Thailand: The Project contributed to the establishment of a data-processing system for industrial tu purse seiners registered in Thailand. Yemen: The Project sent missions in order to assess the status of data collection in that country and propose further actions to improve the quality of the statistics available from Yemen. The Project agreed to provide support for the compilation and computerization of historical data from the artisal fisheries in Yemen; unfortutely, the Project was uble to filize the agreement for these activities to be initiated within Phase II of the Project. The Project contributed substantially to improving the quality of the statistics available at the IOTC, including better catch, effort and, in particular, size-frequency data. In addition, the Project addressed recommendations concerning the fisheries under study which, if implemented by the institutions concerned, may lead to significant improvements in the area of data collection, processing and reporting. On numerous occasions, the IOTC Scientific Committee and other IOTC technical bodies stressed the importance of the activities initiated by the Project, noting that the information collected is of key importance for the assessments of some of the main IOTC stocks.

Users also downloaded

Showing related downloaded files

No results found.