Modelling Anglerfish Discard behaviour in Spanish North Atlantic Coast Fisheries

Onboard sorting process for angler sh species in Spanish North Atlantic (ICES VIIIc, IXa) coastal sheries is reviewed. The length e ect analysis across the years sampled reveled an increasing trend in length of rst retention (L50) since 2000, the year when Minimum Landing Weight (MLW 500g) were implemented. Speci c di erences in the length-based sorting process were found, being the less valuable white angler discarded at larger lengths than the black species; further, the analysis found that discard decision is taken at narrower length range for black angler. This results indicate that shers recognize angler species even at low length sizes, conditioning the degree of adoption of MLW with regards to species relative market value

Some applications of the bootstrap in Spanish Discards Sampling Scheme

Herein we propose a nested boostrap scheme to explore di erent sources of variability in discard data. The proposed tool resamples on trips, hauls within trips and lengthclasess within hauls to include all sources of variability identified in the Spanish DCR sampling program scheme. Megrim (Lepidorhombus wiffiagonis) and Hake (Merluccius merluccius) discard data collected in 2008 from OTB-51 metier operating in ICES Division VI - VII, and Mediterranea DEF-Southern metier operating in the GSA 6S area were considered as case studies. Bootstrap Error and Coeficients of Variation associated to mean discards per trip were obtained and compared with asymptotic estimates. Furthermore, we use the bootstrap to quantify the contribution of the given sources of variability to global variability, and to assess simulated sampling scenarios differing each others in sampling effort. The last application of this method is for detecting outliers in 2008 sampled units (Trips). The good performance of the bootstrap method validates its use to obtain reliable error estimates in further regression and/or classiffication studies on discard data

Anglerfish (Lophius spp.) increasing discards in Spanish OTB fleet (VI-VII ICES). Juveniles availability or sampling artefact?

An update of the yearly estimates of angler sh (black angler (Lophius budegassa) and white angler(Lophius piscatorius) discarded by the Spanish bottom trawl operating in the Northeast Atlantic ocean are presented. Black angler discards increased sharply in the last three year, while UShape with a maximum in 2010 is found for white angler. A 2003 - 2010 sampling methodology review has beeen carried out without detecting any shift in the protocol which could produce overestimation for recent years discards. Fishing covariates related to black angler discard data also indicates that shing practices remain stable along the series. We detect a steady increase in the species rst length of retention L50 from 21; 5cm in 2003 to a range 23cm - 25cm between 2004 - 2008 and 28cm since 2009. We conclude that interaction between the industry adoption of a Minimum Weigth Landing (500g) and the strength of recruitment indices explain the increase in amounts of angler discards

Elasmobranches Results from Spanish Discard Sampling Programme

A discard Elasmobranches species composition estimates for the Spanish bottom otter and pair trawl fleets operating in the Northeast Atlantic ICES Subareas VI, VII, VIII and North IX are presented. Information has been obtained from the “Spanish Discard Sampling Programme” carried out by the IEO. Time series provide information on discarded catch (in weight and number) and length distributions since 2003 to 2009. Eighteen species were selected in order to show the most important ones occurring in Spanish discards. Trip was the sampling unit, being raised to fleet level using fishing effort as auxiliary variable. Discard estimates for these species show high betweenyears variation, exceeding 50% CV in all cases. Further exploratory data analysis was carried for the four most discarded species

Deep Species Results from Spanish Discard Sampling Programme

Estimations of deep species discards from three Spanish bottom otter trawl m etiers operating in the Northeast Atlantic ICES V I, V II, V IIIc and North IXa are presented in this paper. Information has been ob- tained from the `Spanish Discard Sampling Programme' carried out by the IEO. Trip was the sampling unit, being raised to eet level using sh- ing e ort as auxiliary variable. Discard weigth estimates from time series of seven years (2003-2009) is presented for twelve species. Further, dis- card length distributions are presented for those species that have been observed whitin discarded fraction for more than three years. Estimates show high between-years variation in discard amounts, exceeding 35% CV in almost all cases. Results show that the largest amounts of discards of most of the species occur at depths less than 600m. Low market value is the main factor that forces the eet to discard most of deep species

Southern Megrim Species Results from Spanish Discard Sampling Programme

A discard megrims (Megrim, Lepidorhombus whiffiagonis and Four spot megrim, L. boscii) composition estimates for the Spanish bottom otter trawl fleets operating in the Northeast Atlantic ICES Divisions VIIIc and North IXa are presented. Information has been obtained by sampling Spanish fleets under the “Spanish Discard Sampling Programme” carried out by the IEO. Trip was the sampling unit, being raised to different fleet level using fishing effort as auxiliary variable and total fleet landings. Raising to total fleet landings was used for discard fleet estimation due to the lower CV obtained. Time series on discards of both species since 1993 to 2010 are presented. Discard age distributions of both southern megrims species, are also showed. Discard estimates for these species show high between-years variation, exceeding almost 25% CV in almost all cases in both species but with lower values in four spot megrim. MLS and low market value for small fish are the main factors that force the fleet to discard most of megrims species

Estimates on Cephalopods Discards by Spanish NE Atlantic Trawl Fishing Fleets

Yearly cephalopods discard estimations for Spanish trawl eets operating in Northeast Atlantic area (ICES V I, V II, V IIIc and IXa) over the period 2003-2010 are presented. Estimations are aggregated from m etier to shing ground level. Only information for the most important species in terms of discarded biomass and those included in the Data Collection Framework directive are presented. Squid species belonging to the family Ommastrephi- dae and the Octopodidae Eledone cirrhosa were the most discarded species in the northern shing grounds, nevertheless volume discarded of those species are much higher in ICES Sub-area V I V II than in Divisions V IIIc and IXa north. Very low discard values were observed in ICES Division IXa south (Gulf of C adiz), being Octopus vulgaris and Eledone moschata the most discarded species

Trawl Anglerfish Discard Estimates and Patterns in the Spanish Northeast Atlantic Fisheries.

Discards estimates from Spanish bottom otter trawl of anglerfish, Lophius budegassa (black anglerfish) and L. piscatorius (white anglerfish), in Northeast Atlantic Ocean (ICES Sub-areas VI, VII and Divisions VIIIabd) are presented in this paper. Information was obtained by observers on board in different discard programs carried out by Spanish Research Institutes. Total discards obtained by the different raising procedures were very similar and total discard raised by effort (number of trips) as a simple estimator was assumed as the adequate value. Values in weight range from 4 t to 590 t, and from 4 t to 320 t for white and black anglerfish respectively in Sub-areas VI and VII. Length distributions of discarded anglerfish (Sub-areas VI and VII) show that most of the specimens are juvenile individuals. Discards estimations show a high variability in weight and number along the period studied. Yearly abundance of juveniles in the area is a factor to understand the variability of discard quantities. This trend in Sub-areas VI and VII is reflected by similar pattern between juveniles (length < 31cm) discards estimations and recruitment indices (age 0) obtained by French (FR-EVHOES) for black anglerfish, and Irish (IR-IGFS) for white anglerfish. Inter-annual variation may also be explained by legal restriction on minimum weights (DCR) laid down in 2000 due to change in onboard sorting procedures