González-Herraiz, I. (Isabel)

Moura, O. (Olga)

Pérez-Contreras, M.N. (María Nélida)

Quinzán, M. (Marta)

English

Repositorio Institucional Digital del IEO

RCM North Atlantic 2008 report 7213 Annex 4 : Review of the spatial distribution of the Spanish and Portuguese discard sampling in bottom trawlers in Division IXa  Review of the spatial distribution of the Spanish and Portuguese discard sampling in bottom trawlers in Division IXa Working document for the 2008 RCM-NA  Quinzán, M.; Moura, O.; Pérez, N.; González Herraiz, I.  One of the terms of reference of the fourth Regional Coordination Meeting on North East Atlantic (RCM-NEA) held in November 2007 was:  “Propose a regional design and regional protocols for the collection of biological data in the view of the new DCR for the fleet based approach and SGRN recommendations: the proposal should include suggestions for the sampling intensities and precision levels wherever possible In this view, the following aspects will have to be tackled: a.  review the status of the current work carried out on concurrent sampling b.  discard sampling c.  future design and arrangements for collection of biological data (growth/otoliths, maturity, fecundity) and their analysis (age reading, etc.)” During the meeting throughout the discussion of this point the following thoughts were referred:  • Due to the high number of assessed stocks within the RCM NEA area, for which discard information for assessment purposes may be required, there is a need to co-ordinate discard sampling internationally to improve coverage by area and fleet. • The RCM agreed to exchange more detailed data before RCM 2008 to allow mapping of discard work and provide opportunities to discuss co-ordination and cooperation.  • Moreover, it is expected that the initiative taken by ICES (PGCCDBS, 2007) to request a standalone data section in each assessment Working Group report will be implemented as soon as 2008. Such a data section describing the concrete actions needed to improve the quality of the data used, in particular the need to set up discards sampling programmes, will have to be discussed for action during the future RCM. RCM NEA strongly approves the ICES initiative. In order to begin concretely the co-ordination of discards sampling, RCM NEA decided to initiate two case studies which will produce essential elements for discussion in the next RCM. This working document deals with the study case 1. Study Case 1  Review of the spatial distribution of the Spanish and Portuguese discard sampling in bottom trawlers in Division IXa Spain and Portugal carry out several trips with discards observers on board in the bottom trawlers directed to demersal fishes in the ICES Divisions VIIIc and IXa. The aim of this RCM North Atlantic report 2008 73study is analyzing the spatial distribution of the observed trips by the two countries in Division IXa to see if there is sampling overlapping between both countries, and also to compare both sampling and fleets effort distributions. A working document will be produced for discussion at RCM NEA in 2008.   RCM NEA 2007  Recommendations RCM NEA recommends a case study for analyzing jointly the spatial distribution of Portuguese and Spanish discard sampling in IXa and itspresentation for discussion in the 2008 RCM NEA. Follow-up actions hended Each MS to provide positions of the observed trips and spatial distributionof the fleets' effort. Working document for the next RCM NEA. Responsible persons for follow-up actions I. González Herraiz (Spain) and O. Moura (Portugal) Time frame (Deadline) Autumn 2008  The number of samples to be collected in Portuguese bottom trawl fisheries (Crustacean and Fish fleets) was estimated from the total number of trips of the fleet (vessels above 15 m), for the years 2004 and 2005.  During 2007 Portugal sampled 50 trips by on-board observers in the bottom-trawling fleet in Div. IXa (38 trips on fish fleet and 12 trips on crustacean fleet) (Technical REPORT – 2007 Portuguese Program for the collection of fisheries data Table 7.1. - “Discard sampling”). Figures 1 to 5 show the spatial distribution of Portuguese and Spanish discard sampling in IXa, during the period 2005-2007.    VIIIbVIIIc414243444510 5 010 5 04142434445Golfo deVizcayaEspañaSituación Lances Obs. a BordoArrastre VIIIc-IXa  Figure 1 - Spatial distribution of sampling hauls performed from the Spanish trawl fleet in Divisions VIIIc and Ixa  RCM North Atlantic 2008 report 74 VIIIbVIIIc414243444510 5 010 5 04142434445Golfo deVizcayaEspañaSituación Lances Obs. a BordoGran Abertura Vertical  Figure 2 - Spatial distribution of sampling hauls performed from the Spanish High Opening Bottom Trawl fleet in Divisions VIIIc and IXa.     VIIIbVIIIc414243444510 5 010 5 04142434445Golfo deVizcayaEspañaSituación Lances Obs. a BordoPareja VIIIc-IXa  Figure 3 - Spatial distribution of sampling hauls performed from the Spanish Pair Bottom Trawl fleet in Divisions VIIIc and IXa.  RCM North Atlantic report 2008 7510.5 10.0 9.5 9.0 8.5 8.0 7.5Longitude (W)36.537.037.538.038.539.039.540.040.541.041.542.0Latitude (N)Área IXaDistribuição dos Lanços Obs a Bordo+ Arrasto da Frota de Crustáceos  Figure 4 – Spatial distribution of sampling hauls performed from the Portuguese crustacean trawl fleet in Division IXa. 10.5 10.0 9.5 9.0 8.5 8.0 7.5Longitude (W)36.537.037.538.038.539.039.540.040.541.041.542.0Latitude (N)Área IXaDistribuição dos Lanços Obs a Bordo+ Arrasto da Frota de Peixes  Figure 5 - Spatial distribution of sampling hauls performed from the Portuguese fish trawl fleet in Division IXa. RCM North Atlantic 2008 report 76The observation of the figures allows concluding that the spatial distribution of the discard sampling effort performed in Spanish and Portuguese fleets, conducted routinely, do not overlap. Nevertheless, Spain has a short and sporadic number of vessels operated in Portuguese’s waters based in only one Spanish port (Marín). Those vessels are not sampled under the DCR due to the reduced number of effort in the area and the long duration of the trip. That behaviour makes very expensive to sample this fleet when it operates in Portuguese waters. Trips from the same port but fishing in Spanish waters are shorter and they are sampled under the DCR.  Over the years 1994, 1997, 1999 and 2000, Spain carried out 15 discard sampling experiments with Spanish trawl vessels fishing in Portuguese waters (below parallel 42º00’00’’). Table 1 shows the data obtained in these experiments in order to compare discard percentage and total catch composition of the Spanish trawler fleet in both Spanish and Portuguese waters in ICES Division IXa. Caught species subjected to DCR are displayed.   Specie % CV % CV % CV % CVAphanopus carbo 100.0 656 100.0 387  + 656  + 387Argentina sphyraena 91.9 181 99.6 154 0.3 163 0.4 155Boops Boops 0.0  + 656Cancer pagurus 0.0 0.0  + 240  + 214Centroscymnus coelolepis 100.0 511 100.0 219 0.1 511  + 219Helicolenus dactylopterus 72.4 226 50.5 209 0.1 230 0.3 171Homarus gammarus 0.0 0.0  + 479  + 387Hoplostethus atlanticus 100.0 280  + 280Lepidorhombus boscii 29.8 109 20.6 155 2.0 87 2.1 103Lepidorhombus whiffiagonis 16.2 319 4.3 268  + 227 0.1 168Loligo vulgaris 3.0 656 8.7 387  + 340  + 245Lophius piscatorius 0.0 0.5 387 0.3 184 0.6 110Merluccius merluccius 15.8 259 20.4 140 4.5 106 3.8 98Micromesistius poutassou 80.2 114 78.6 156 27.8 89 6.8 128Mullus surmuletus 89.9 656 0.0  + 591  + 370Nephrops norvegicus 2.0 209 3.7 180 0.7 147 0.6 74Octopus vulgaris 1.4 656 2.0 351 0.1 222 0.5 156Pagellus acarne 0.0 0.0  + 390 0.1 316Parapenaeus longirostris 84.8 656 97.9 327  + 656  + 321Raja brachyura 48.5 278  + 229Raja clavata 0.0 19.2 387  + 656 0.2 387Raja montagui 0.0  + 387Raja naevus 82.1 286 0.5 264Rajidae 11.7 623 5.4 387 0.1 582 0.1 306Scomber japonicus 100.0 387  + 387Scomber scombrus 9.5 288 40.4 230 3.8 291 0.5 205Solea solea 0.0 0.0  + 574  + 284Trachurus trachurus 1.7 359 14.8 241 4.0 233 1.4 322Trisopterus luscus 29.4 271 16.0 210 2.8 157 1.7 143Other species no subjected to DCREledone cirrhosa 2.3 593 5.6 228 2.9 153 1.0 100Macroramphosus scolopax 100.0 587 100.0 214 1.9 435 19.7 214Munida spp. 99.9 409 71.7 105 2.3 390 0.3 147Polybius henslowi 100.0 285 100.0 191 26.0 273 21.5 191Scyliorhinus canicula 81.5 165 90.9 198 0.4 150 6.3 184Portuguese watersSpanish watersPortuguese watersSpanish watersDiscard percentage Total catch + less than 0.1 DCR = Data Collection Regulation  Table 1. Spanish trawler fleet Discard weight percentage of Caught Species subjected to DCR and Spanish trawler fleet Total Catch weight composition in percentage of species subjected to DCR  RCM North Atlantic report 2008 77As can be seen in Table 1, species composition subjected to DCR of the Spanish and Portuguese fleets are very similar though some differences can be pointed. However, total catch percentage appears to be different in species that are not regulated under DCR (other species). For blue whiting (Micromesistius poutassou), the observed total catch percentage seems to be higher in Spanish waters (28%) than in Portuguese waters (7%). Species as blond ray (Raja brachyura), cuckoo ray (Raja naevus) and Atlantic mackerel (Scomber japonicus) are catched in Portuguese waters but not in Spanish ones. Otherwise, bogue (Boops boops) is caught and retained by the fleet operating in Spanish waters. Moreover, both fleets present very similar discard patterns for species regulated by DCR. Differences can be pointed out in red mullet (Mullus surmuletus), which is discarded on vessels operating in Spanish waters, but retained when working in Portuguese ones. Similar values for discard percentage are also observed for not subjected to DCR species.  In conclusion, differences, in discard and total catch estimations, are non relevant especially due to the usual high variability rates in discard and catch composition estimation. As a consequence, sampling the Marín fleet in Spanish waters is representative of the discard produce for this port in both Spanish and Portuguese waters.  

Review of the spatial distribution of the Spanish and Portuguese discard sampling in bottom trawlers in Division IXa

http://www.repositorio.ieo.es/e-ieo/bitstream/10508/3446/1/WD%20Discards%20Portugal-Spain.pdf

Review of the spatial distribution of the Spanish and Portuguese discard sampling in bottom trawlers in Division IXa

Abstract

Similar works

Full text

Available Versions

Repositorio Institucional Digital del IEO