Morphometric and meristic variation in Argentine hake (Merluccius hubbsi) and southern hake (Merluccius australis) from the southwest Atlantic.

Samples of Merluccius hubbsi (N=147) were collected from the southwest Atlantic, in the high seas at 42o S and 46oS and from the waters around the Falkland Islands. A sample of M. australis (N=23) was also collected in Falkland Islands waters. Variation in the population structure was investigated using multivariate analysis of a total of external and skeletal morphometric data, counts of fin rays and teeth, and measurements on scales. All measurements were standardised to mean body size and each character set was analysed separately. Principle components analysis and discriminant analysis were used to identify differences between M. hubbsi from different areas and differences between the two species. The results indicate the presence of two groups of Merluccius hubbsi within the study area, one found on the high seas and one in the waters around the Falkland Islands. Results are discussed in relation to the reproductive and trophic migrations of M. hubbsi, the relative importance of genetic and environmental differences, and the results of similar studies from the southwest Atlantic

Identifying the best fishing-suitable areas under the new European discard ban

The spatial management of fisheries has been repeatedly proposed as a discard mitigation measure. A number of studies have assessed the fishing suitability of an area based on units of by-catch or discard per unit effort. However, correct identification of fishing-suitable areas should assess biomass loss with respect to the benefits. This study therefore, proposes the analysis of by-catch ratios, which do represent benefit vs. loss and are standardized to a wide range of effort characteristics. Furthermore, our study proposes the use of two ratios: the proportion of total unwanted biomass out of the total catch as an indicator of the overall ecological impact, and the proportion of unwanted but regulated species biomass as a proxy for the economic impact on fishers resulting from the new European discard ban that prohibits the discard of regulated species. These discard ratios are modelled by means of a Bayesian hierarchical model, specifically, a spatio-temporal beta regression model, which has several advantages over the traditional arcsine transformation. Results confirm the standardizing capacity of by-catch ratios across vessels and identify at least two economically fishing-suitable areas where discards ratios are minimized by reducing unwanted catch

Analysis of the evolution of hake (Merluccius hubbsi and Merluccius australis) catch and effort by Spanish vessels operating in the Patagonian shelf area since the beginning of this industrial fishery

The hake fishery (Merluccius hubbsi and Merluccius australis) is one of the most important ones for Spanish vessels operating in the Southwest Atlantic. Both species are widely distributed along the Patagonian shelf, although M. australis occupies mainly more southern waters. This paper presents a historical review of fishery data on the Spanish fishing fleet operating in the SW Atlantic collected and collated during the EC Study Project 99/016 “Data collection for stock assessment of two hakes (Merluccius hubbsi and M. australis) in International and Falkland waters of the SW Atlantic”, in order to analyse the evolution of catch and effort in the hake fishery since 1983 to 2000. Data on landings and effort by Spanish vessels from 1983 onwards were utilised to study trends and shifts within the fishery. These data were provided by Asociación Nacional de Armadores de Buques Congeladores de Pesca de Merluza (ANAMER), the most important Spanish ship-owners fishing association operating in distant fishing grounds. Catch and effort data collected by observer’s programmes carried out by Instituto Español de Oceanografía (IEO) and the Falkland Islands Government Fisheries Department (FIGFD), as well as by observers provided by the project were used to estimate CPUE by area and season.The data included landings in kgs by commercial size category of hake (both species together) and effort made by vessels appertaining to ANAMER in number of fishing days and number of vessels by vessel size category. Conversion factors obtained by scientific observers onboard of these vessels were used to obtain the whole catch from landings. Total effort of the Spanish fleet was estimated from ANAMER logbooks, assuming a similar pattern for the whole fleet and taking into account the different ratio of ANAMER fleet compared to the total Spanish fleet. An increase of the catches and effort was observed from 1983 to a maximum in 1990 coinciding with the closure of Namibian fisheries. After that, catches and effort decreased corresponding to the development of the Greenland halibut fishery in the NW Atlantic, until its stabilisation from 1993. CPUE showed different patterns of fishing activity by area and season

. A trophic latitudinal gradient revealed in anchovy and sardine from the Western Mediterranean Sea using a multi-proxy approach

This work combines state-of-the-art methods (DNA metabarcoding) with classic approaches (visual stomach content characterization and stable isotope analyses of nitrogen (δ15N) and carbon (δ13C)) to investigate the trophic ecology of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) at high taxonomic and spatial resolution in the Western Mediterranean Sea. Gut contents observed are in accordance with the dietary plasticity generally described for anchovy and sardine, suggesting a diet related to the opportunistic ingestion of available prey in a certain area and/or time. Genetic tools also showed modest inter-specific differences regarding ingested species. However, inter-specific and intra-specific differences in ingested prey frequencies and prey biomass reflected a latitudinal signal that could indicate a more effective predation on large prey like krill by anchovy versus sardine, as well as a generalized higher large prey ingestion by both species southwards. In fact, both species presented lower δ15N in the northernmost area. This latitudinal gradient indicates changes in the trophic ecology of anchovy and sardine that coincide with previously described better biological conditions for fish in the southern part of the study area as well as higher landings of both species in recent years.En prensa2,92

Modeling discards in Trawling Mediterranean Northern Alboran Sea Fishery

Target and Bycatch species metrics estimated from fishery-dependent data were explored to assess their use in governance of habitat conservation in respect to fisheries. Fishing data collected by onboard observers in otter-trawl boats between 2011 and 2012 at monthly sampling frequency in the Alboran Sea (Western Mediterranean) were used to build maps of sensitivity to fishing stress. Maps were drawn by means kriging interpolation techniques of biomass and abundance (Catch Per Unit of Effort, CPUE) in kilogram and number per fishing hour of blue whiting (Micromesistius poutassou), European hake (Merluccius merluccius), and red mullets (Mullus barbatus and Mullus surmuletus) target species, seabreams (Pagellus acarne, Pagellus bogaraveo, and Pagellus erythrinus), and mackerels (Trachurus mediterraneus, Trachurus trachurus, and Trachurus picturatus) bycatch species and Bogue (Boops boops) bycatch discarded species. Modelling discards by means Generalised Additive Models (GAMs) use environmental (sea surface temperature and chlorophyll-a from satellite data and NAO climatic index); spatial (latitude, longitude, depth and port) and temporal (season, haul duration, moon phase), as well as technical (boat length and power) explanatory variables. The main causes of discards, for both target and bycatch species, are associated to the seasonality of the recruitment and the changes on the spatial distribution of habitat preferences along their ontogeny. Environmental variables did not reveal significant effects, showing that operational oceanography standard products must be not enough to assess discards, and therefore products providing information on specific ecological processes to discards must be designed with this purpose. In Bycatch species, such as sea breams, mackerels and bogue, discards were also highly dependent of the port and boat (fleet/boat strategies, power, etc, and market preferences). The higher discards corresponded to these bycatch pelagic or bentho-pelagic species. Keywords: Discards, Otter-trawl fisheries, fishery conservation, operational oceanography, spatial modelin

Data collection for stock assessment of two Hakes (Merluccius Hubbsi and M. Australis) in international and Falkland Waters of the SW Atlantic

Study Project 99/016 “Data collection for stock assessment of two hakes (Merluccius hubbsi and M. australis) in international and Falkland waters of the SW Atlantic” ran from January 2000 to December 2001. The main objective of the project was the collection and collation of already existing and newly acquired fishery and biological data needed for preliminary assessment of two hake species occurring in the study area. In addition to this basic remit, additional objectives included the creation of a common database, study of spawning seasons and areas, discard pattern and length-frequency composition of target and non-target species, estimation of annual by-catch rates, analysis of trophic relationships, marine mammals by-catch and sightings, morphometric analysis for stock differentiation, and developing GIS applications for analysis of the data collected. Historical fishery and biological data series available from IEO and FIGFD (since 1988 and 1987 respectively) were provided to the project. New fishery and biological data were collected by scientific observers provided by IEO, ANAMER and FIGFD, and placed on board Spanish fishing vessels operating in the study area during the project period. Data on fishing activity included effort, catches and discards of target and non-target species on a haul-by-haul basis. Biological information (size, sex, maturity stage, etc) of target and non-target species was recorded on a daily basis. Data on landings and effort were provided by ANAMER to its subcontractor (MG OTERO) for processing and estimation of total catch and effort of the whole Spanish fishing fleet in the area; MG OTERO was also responsible for organisation of observers in collaboration with ANAMER staff in Vigo and Port Stanley. Ancillary data on location, time of fishing, depth, SST, SBT, sea roughness, wind, etc, was recorded on a haul-by-haul basis. This type of information was essential for development of GIS at AU to relate the species distribution to physical and environmental factors. Other information collected was about by-catches and sightings of small cetaceans and seabirds, and biological samples such as otoliths, stomachs and whole specimens of hakes for subsequent studies on growth (IEO, FIGFD), diet and morphometrics (AU). All the historical and new data collected during the project were collated and integrated into a common database designed by all participants and built at IEO. The information was used for preliminary assessment of two hake populations co-ordinated by RRAG during a workshop held in London in July 2001. All these data will be analysed and written up for future publications. Discard rates of target species were generally low in all areas and seasons with the highest discard rate for Notothen sp. (around 100% of the catch). Illex squid was found to be the major by-catch for hake fishery in the 46 S area. IEO observers reported data on incidental catches of marine mammals and sea birds since 1993 and the analysis of this information was made by AU. The observed mortality in the fishing gears comprised small numbers of black-browed albatross, gentoo penguin and the hourglass dolphin. The species most frequently sighted was the Peale’s dolphin, although this species did not appear in by-catches, followed by the hourglass dolphin. The project provided an opportunity to collect and integrate for the first time at European level the necessary fishery and biological data for the development of partial stock assessment for the future rational management of the fisheries in the area. Such management is needed for the sustainability of the commercial fisheries, the conservation of the onshore and offshore jobs and the supply of fish to the most important markets worldwide.EUROPEAN COMMISSION DIRECTORATE GENERAL FISHERIES – DG XI