Review of stock assessments carried out thus far

Review of stock assessments carried out thus far

Note: A benchmark workshop on this stock (WKDEEP) is scheduled by ICES in February 2010.

No assessment has been carried out in 2008, 2009. Some work has been done to use CPUE from the French Industrial DeepSea Fishery as an indicator of trends in the deepwater fishery.

No formal assessment has been carried out in 2008, 2009.

Note: A benchmark workshop on this stock (WKDEEP) is scheduled by ICES in February 2010.

Both stock are merged into a single “siki sharks” stock. The term “siki” is used to describe the combination of leafscale gulper shark and Portuguese dogfish. Although these species have very different biological traits, it has been necessary for ICES to combine them for assessment purposes. This is because landings data for both species were combined for some of the main countries for most of the time since the beginning of the fishery. The term “siki” as used here does not have the same meaning in French commercial fisheries, where it encompasses all commercially exploited deep‐water sharks.

Note: A benchmark workshop on this stock (WKDEEP) is scheduled by ICES in February 2010.

2. 
   How is the frequency of assessments linked to the advisory and management cycle?
   

Fisheries for deep-water species in the NE Atlantic were largely unregulated from their commencement in the 1970s to the early 2000s. Following repeated ICES advice that most stocks were “outside safe biological limits,” that “fishing effort on specified stocks should be reduced” while on others “fishing should not be allowed to expand faster than the acquisition of information necessary to provide a basis for sustainable exploitation” and that “new fisheries should be permitted only when fisheries expand very slowly, and are accompanied by programs to collect data which allow evaluation of stock status,” it was not until January 2003 that the EU introduced biennial TACs for deep-water species, including roundnose grenadier. As a first step towards effort management, a vessel licensing scheme with aggregate power and capacity of deep-water fishing vessels capped to levels observed in the years 1998–2000 was implemented.

These TACs are revised every second year. The EU TAC and national quotas from member countries apply to all vessels in EU EEZ and to EU vessels in international waters. For Roundnose Grenadier and Black Scabbardfish, ICES recommends that catches should be constrained to 50% of the level before the respective expansions of the fisheries. For Greater Forkbeard, ICES advice state that the landings of greater forkbeard are mainly bycatch from traditional demersal trawl and longline fisheries targeting species such as hake, megrim, monkfish, ling, blue ling, etc. Fluctuations in landings are probably the result of changing effort on different target species and/or market prices and are not necessary linked with changes in the resource abundance. The species should not be managed in a single species context and any advice should take into account advice on other species/fisheries. For all the above species, ICES recommends those fisheries should not be allowed to expand unless it can be demonstrated that they are sustainable. There is no management objective for the above species.

Portuguese dogfish, leafscale gulper shark, birdbeak dogfish (Deania calceus), kitefin shark (Dalatias licha), greater lantern shark (Etmopterus princeps), velvet belly (Etmopterus spinax), black dogfish (Centroscyllium fabricii), gulper shark (Centrophorus granulosus), blackmouth dogfish (Galeus melastomus), mouse catshark (Galeus murinus), and Iceland catshark (Apristurus spp). 

2. 
   Input data
   

1. 
   For all exploratory assessments or the latest benchmark or update assessment, please list the input data citing length of time-series (where appropriate) and source
   

-Total international landings 1990-2008 (ICES WGDEEP)

-Length distribution 1990-2008 (ICES WGDEEP)

-Samples of discards 1997-2001 & 2004-2006 (ICES WGDEEP)

-Aggregated Age-length key (ICES WGDEEP)

-Weight length relationships 1999 (Lorance, pers comm.)

-Effort: French Industrial Deep Fisheries haul by haul database 1992-2008

-Length distribution per depth strata (literature, scientific surveys)

-Total international landings 1988-2008 (ICES WGDEEP)

-Effort: French Industrial Deep Fisheries haul by haul database 1992-2008

Greater forkbeard

-Total international landings 1988-2008 (ICES WGDEEP)

-Estimates of discards data by the Basque Country trawler fleet 2003-2008 (ICES WGDEEP)

-LPUE by the Basque Country trawler fleet 1996-2008 in VI, VII, VIII (ICES WGDEEP)

-Length distribution in Porcupine surveys 2001-2008 (ICES WGDEEP)

Portuguese dogfish and leafscale gulper shark

-Total international landings 1988-2008 (ICES WGEF)

-Landings by species (sharks and bycatch) by gear and area for the UK fishery in VIII and IX (ICES WGEF 2007)

- Landings by species (sharks and bycatch), gear, effort, depth and area for the Russian vessels in I, V, VI and IX (ICES WGEF 2009)

- French industry CPUE by ICES subareas (ICES WGEF 2007)

- Portuguese longline CPUE in IX (ICES WGEF 2007)

3.2.2 Are there any aspects of data (quality, temporal and spatial extent, time series, availability, accessibility, flow) that

• 
  Landings data are considered uncertain in Division XIIb, because unreported landings may occur in international waters. In addition to this, all national landings data were not reported by new ICES divisions and some landings were allocated to divisions according to knowledge of the fisheries from the working group. Lastly, significant unallocated landings occurred in 2005. Substantial uncertainties and misreporting in XIIb has led to exclude this area from the ICES assessment.
  

• 
  Times series of discards have many gaps especially at the beginning of the fishery and in recent years. Length distribution of landings has substantially changed through time therefore it can be assumed that the discards distribution has also changed.
  

• 
  Age-Length Key is aggregated due to a low number of samples for the whole time series (rather than using ALKs only for short periods e.g. annual ALKs). Age reading method is not validated for this stock and is proven to be difficult requiring specific training.
  

• 
  The time-series of the Spanish catch in Subarea XII was revised according to Statlant data in 2009. No catch data were available for the Spanish trawling fleet operating on the Northern and Western Hatton Bank (Divisions VIb1 and XIIb) in 2008.
  

• 
  Maturity: so far, the information available for ICES Subareas Vb, VI, VII and XII consistently points out to the predominance of immature small specimens.
  

• 
  Times series of LPUE is not reliable for 2008 as it includes only a few fishing days and will not be available in future.
  

• 
  Data from the French fishing industry will provide more reliable estimates of CPUE. However, at present time series are too short to be useful in stock assessments. Therefore, CPUEs from French logbook data are presently used. However, several factors, such as seasonal and depth effects and species directivity affect commercial CPUEs and these can be very difficult to interpret.
  

• 
  This stock appears to be data deficient. ICES advice since 2006 repeats that “ Fisheries on greater forkbeard should be accompanied by programmes to collect data.”
  

• 
  The species should not be managed in a single species context and any advice should take into account advice on other species/fisheries.
  

• 
  Estimates of total landings is a mix of deepwater sharks and sometimes integrates a small component of other species. France has presented a split of French landings, by species in 2008 but the rations were not used by WGEF because they were derived from 1990s data on species abundance by depth which is no longer valid, as a consequence of the declining relative abundance of Portuguese dogfish.
  

• 
  Discards: in the early years of the fishery, discarding was thought to be negligible in the majority of trawl and longline fisheries although some discarding may have occurred in the first years before markets were fully developed. With the quotas for deepwater sharks becoming restrictive, it is likely that discarding has increased as a consequence of management regulations (e.g. bycatch limits; quota may be limited for some fleets). Discarding can be expected to be greatest where there are relatively high TACs for other species caught along with deepwater sharks. In northern areas, discarding is considered to be lower, because shark abundance in mixed fisheries is much lower in recent years. In southern areas, where shark abundance is relatively stable, it may be expected that discarding has increased, due to restrictive quotas for sharks. Between 2001 and 2004, Irish trawlers have discarded their entire catch of leafscale gulper sharks. This was based on crew preferences, not market factors. Some discarding of rotten deepwater sharks, due to excessive soak times, has been recorded in gillnet fisheries (STECF, 2006).
  
• 
  There are no reliable estimates of levels of misreporting of these species but it is believed to be a minor problem. Immediately prior to the introduction of quotas for deepwater species in 2001, it is believed that some vessels may have logged deep-water sharks as other species in an effort to build up track record. It is also likely that, before the introduction of quotas for deepwater sharks, some gillnetters may have logged monkfish as sharks. Since the introduction of quotas on deep-water sharks in 2005, it is likely that some under-reporting has occurred. It can be expected that some vessels with restrictive quotas for deepwater fish may misreport more valuable species as deepwater sharks. IUU fishing is also known to take place, especially in international waters.
  

• 
  No new length distribution has been made available since 2006.
  

• 
  WGEF repeatedly finds it difficult to quantify landings data when MS report data for both live weight and for livers. This can lead to duplication of data and overestimation of landings. WGEF asks all MS to explain how landings of livers are raised to total live weight, and to report if duplication could be happening. Those nations undertaking scientific fisheries for deep water species can take large quantities of fish (e.g. deep water sharks) and should ensure that these catches are reported accordingly.
  

2. 
   Assessment method(s) used
   

1. 
   Justification of the method: for exploratory assessments please describe reasons for selecting the method(s) used. Was any guidance available as to the type of method to use? If so please describe.
   

This stock is in a data-poor situation with uncertainties in XIIb, and about the level of discards. Therefore, only exploratory assessments can be performed. Discards were included in 2008 (WGDEEP, 2008). In 2009 a comparison between assessments including or not discards or using a rebuilt catch time series from science surveys and industrial data showed biomass in recent year is at the same level for all methods (Pawlowski and Lorance, 2009). The inclusion of discards does not substantially change the assessment in recent years. At the beginning of the fishery, levels of biomass are likely to differ between methods. However, there is not enough information on the level of discards in the early 1990s to make sound assumptions that could give credentials towards a particular method to estimate biomass.

No assessment is performed other than reviewing trends in CPUEs from the French industry database. However the time series is too short to be useful for stock assessment.

No assessment is performed for this stock.

No assessment has been carried out since 2006 other than reviewing trends in CPUEs.

2. 
   Benchmark: for benchmark assessments please describe agreed best practise and rationale for selection.
   

A benchmark of this stock is scheduled in February 2010 (ICES WKDEEP). Due to uncertainty in the landings occurring in division XIIb, this area has been excluded from the assessment. As a preparatory process, the main challenges (changes in the fishing depth, discards, uncertainties on ALKs) with the assessment and available data have been presented during the ICES Method Working Group (WGMG, 2009) and some work was performed to quantify the effect of uncertainties on age-length key over the assessment. The member of the working group considered age- or length- based models not adequate for this stock and suggested other approaches such as analysis of commercial LPUEs and life stage-based model. Uncertainties about discards and errors from ALKs are possibly the major weaknesses of the assessment for this stock.

No benchmark assessment has been performed.

A benchmark of this stock is scheduled in February 2010 (ICES WKDEEP).

A benchmark of this stock is scheduled in February 2010 (ICES WKDEEP).

3. 
   Uncertainty: how is uncertainty addressed in all types of assessments?
   

Exploratory assessments have not included so far uncertainties. Uncertainties on ALKs and level of otolith samplings have been included in a benchmark assessment by bootstrapping the ALK and evaluating the effects for the assessment of using ALKs of different sizes.

These stocks have no assessment due to the lack of information to perform assessments.

These stocks have no assessment due to the lack of information to perform assessments.

These stocks have no assessment due to the lack of information to perform assessments.

3.3.4 Multispecies: is your stock included in any multi-species assessments? If so please describe. If not should it? If

yes, please describe a suitable way to go forward
There are some developments to do here. I think this is an item for the case study working groups that needs to be prepared by several SC and WP leaders. I can write some background developing the following aspects:

• 
  monospecific assessment have been mostly exploratory, poorly reliable, most often strongly driven by a single time series of abundance index from the French trawl fishery;
  
• 
  it is unlikely that multispecies dynamic model can provide any reliable figure useful for management;
  
• 
  abundance index need to be revisit using (1) longer time series now available (more years with both additional recent years and files from 1984 put back into the current format of the Ifremer statistics database). In addition to this archive data back to 1972 have also been made available recently (at least years 1972-79 being incomplete and reliability need checking);
  
• 
  tally book data on a haul by haul basic allows for better assessment of the impact of fishing tactics on catch. This could allow for a better interpretation of trends in abundance indexes. The most obvious example is with change over the fishing depth over time
  
• 
  observation data also provide knowledge of the species composition of the catch according to fishing strategy
  

Nevertheless, it seems unlikely that multispecies assessment can be carried out in the sense of dynamic model results. The project should consider developing range of indicators by species, for groups of species and the total catch. This should provide some multispecies assessment to analyse questions such as:

• 
  did the proportion of (1) blue ling; (2) roundnose grenadier; (3) black scabbardfish; (4) roundnose grenadier and black scabbardfish combined; (5) deepsea sharks ; (6) deepwater species vs other species (monkfish/megrim, saithe ...) varied over time ?
  
• 
  what are the factors for these variations (depth/latitude/gear)?
  
• 
  base on this how are the species ranking is term of proportion of biomass reduction (starting from any virgin/initial level)
  
• 
  to which extend does this allow to set what should be the relative levels of each species TAC?
  

5. 
   Retrospective analyses: do assessments include retrospective analyses?
   

No retrospective analysis is performed on the Roundnose Grenadier assessment.

3.5.8 Has this rule been agreed with all stakeholders?

Estimates of biomass at the beginning of the fishery are compromised by the lack of information on discards and efforts. Exploratory assessments has shown the initial estimates are highly sensitive on the assumptions made about discards distribution and fishing efforts (WGDEEP, 2009). Russian data from the 1970s-80s estimated stock biomass to be between 400 000 and 700 000 tons.

3.6.2 Were the packages/programs used suitable for use by scientists with little or no experience of them?

3.6.3 If not, how could they be improved?

Should we describe the ICES process here (advice drafting group, ACOM etc..)?

3.7.1 Were the assessments subjected to quality appraisal and/or peer review and if so how and by whom?
Assessments are presented during the WGDEEP plenary session and reviewed by the experts attending the working group.
3.7.2 What were the outcomes for the latest benchmark/update assessment and for all exploratory assessments?
Roundnose Grenadier Vb, VI, VII, XIIb

This species presents major assessment challenges largely driven by: life history characteristics (long lived (ca. 60 years) and slow growing), changes in exploitation pattern resulting from changes in the geographical and depth distribution of trawl fisheries in relation to stock distribution, a lack of fisheries independent survey data, and discontinuity in the availability of time series discard data (fisheries on this stock generate high discards) and of age data. Abundance indices based on French trawl catch and effort data are available but their use in assessments is problematic because of changes in spatial and depth distribution of fishing and also changes fleet composition/fishing power. Time series length distribution data are available for French trawl landings. Time series haul by haul data on catch and effort by French trawlers, collected in collaboration with the industry, is now available.

Some alternate methods to stock assessments to estimate stock trends are necessary. Possible options for a benchmark include refining LPUE calculation from EU-Logbook data, use additional data. For this latter, the French tallybooks database seem to be an interesting opportunity as it is more accurate than EU logbooks, being haul by haul and including data on fishing depth (ICES WGDEEP, 2009).

This is a gadoid species and is considered likely to exhibit typical gadoid life history characteristics, although these are not known with any accuracy. Commercial landings are significant but this almost entirely a bycatch species taken in other fisheries. Exploratory assessments have not yet been attempted.

These species are mostly long lived (up 60 years). Length and age data are not available and historical landings data are not available by species (although in recent years the quality of landings data has improved). Haul by haul data from French trawlers fishing in Vb, VI and VII by species back to the mid‐1990s were made available in 2008. Directed fisheries for these species are currently not permitted but they are still taken as a bycatch in other fisheries.

• 
  Age reading technique on RNG needs to be properly validated.
  
• 
  Haul by haul database from the French Industrial DeepSea Fishery should be analysed.
  

• 
  Not relevant as no assessment has been carried out other than reviewing trends in CPUEs.
  
• 
  Haul by haul database from the French Industrial DeepSea Fishery should be analysed.
  

• 
  No assessment has been attempted yet. The species should not be managed in a single species context and any assessment should take account of this.
  

• 
  Not relevant as no assessment has been carried out other than reviewing trends in CPUEs.
  
• 
  Haul by haul database from the French Industrial DeepSea Fishery should be analysed.
  

• 
  Information on discards at the beginning of the fishery would be helpful to get information on the catch level in the early 1990s in order to estimate stock biomass.
  

• 
  Time series of CPUE is too short to be useful for stock assessment.
  

• 
  As stated in the ICES advices since 2006, fisheries on greater forkbeard should be accompanied by programmes to collect data. Sufficient data may provide basis to develop an assessment.
  

• 
  Length, age data and historical landings data should be available by species.
  

4. 
   
   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 3.16 Mb.
   
   Share with your friends: