We analysed the relationships between climatic indices, population parameters (abundance, recruitment and spawning stock) and catchability of hake and red shrimp in the trawl fishery off Balearic Islands (western Mediterranean

Carbonell, A. (Ana)

Guijarro, B. (Beatriz)

Hidalgo, M. (Manuel)

López-Jurado, J.L. (José Luis)

Marcos, M. (Marta)

Massutí, E. (Enric)

Monserrat, S. (Sebastià)

Moranta, J. (Joan)

Oliver, P. (Pere)

English

Repositorio Institucional Digital del IEO

 Rapp. Comm. int. Mer Médit., 38, 2007THE INFLUENCE OF OCEANOGRAPHIC SCENARIOS ON THE POPULATION DYNAMICS OF DEMERSALRESOURCES IN THE WESTERN MEDITERRANEAN: HYPOTHESIS FOR HAKE AND RED SHRIMP OFFBALEARIC ISLANDSE. Massutí 1 *, S. Monserrat 2, P. Oliver 1, J. Moranta 1, J.L. López-Jurado 1, M. Marcos 2, M. Hidalgo 2, B. Guijarro 1, A.Carbonell 11 IEO- Centre Oceanograﬁc de les Balears, Moll de Ponent s/n, 07015 Palma de Mallorca, Spain - enric.massuti@ba.ieo.es2 CSIC-UIB Institut Mediterrani d’Estudis Avançats, Miquel Marquès 21, 07190 Esporles, SpainAbstractWe analysed the relationships between climatic indices, population parameters (abundance, recruitment and spawning stock) and catcha-bility of hake and red shrimp in the trawl ﬁshery off Balearic Islands (western Mediterranean).Keywords : Demersal, Recruitment, Fisheries, Hydrography, Balear Islands.As in other areas of the western Mediterranean, the hake ( Merlucciusmerluccius) and the red shrimp ( Aristeus antennatus), two target speciesfor the trawl ﬁshery off Balearic Islands, exhibited inter-annual ﬂuc-tuations in landings during the last decades. Within the IDEA project(www.ba.ieo.es/idea) we have studied relationships between some cli-matic indices and parental stock, recruitment and accessibility to trawlﬁshery for these two species.Available annual catch per unit effort (CPUE; as kg/HP) data series for theperiod 1960-2004 were used as a proxy for the abundance of these species.Their population parameters recruitment (R) and spawning stock biomass(SSB) could be obtained (for 1980-2004 for hake and for 1992-2004 forred shrimp) from assessments developed within the framework of the Gen-eral Fisheries Commission for the Mediterranean. As environmental data,the meso-scale IDEA index was used [1]: higher and lower values indicateminor and major presence of WIW for the Ibiza channel, the followingspring respectively, which determine the spring-summer oceanographicscenarios around the Balearic Islands. Other large-scale climate indices,North Atlantic Oscillation (NAO) and Mediterranean Oscillation (MO),were also used. These indices could determine the climatic conditionswhere Mediterranean intermediate waters which could affect hake and redshrimp (WIW and LIW, respectively) are formed. Data series of environ-mental variables (NAO, MO and IDEA indices) and population dynamicsparameters for hake and red shrimp (CPUE, R and SSB) used are shownin Figure 1. To analyse possible links between large- and meso-scale in-dices with the population dynamics of both species, two approaches havebeen used: (i) stock-recruitment relationships (SRR) from Ricker andBeverton-Holt models, by incorporating sequentially environment factors;(ii) generalized additive modelling, both classical general and thresholdnon-additive models were considered, which simulate an abrupt changein explicative variables across different phases (time periods or climaticindex values). The strategy of analysis has been to consider the inﬂuenceof two climatic indices for each species: the regional IDEA index and oneglobal index (NAO for hake and MO for red shrimp). MO index valueswere considered with a -5 years time lag, because available informationestimates that LIW requires up to 5-6 years for reaching the western basin.To avoid the inﬂuence of trends in CPUE, R and SSB, these populationparameters have been conveniently detrended.A negative signiﬁcant relationship between NAO index and abundance(modelled by CPUE) and SSB of hake were found, being this effect moreevident during the period 1960-1980. Results also suggest that density-dependent and environmental factors affect its R, both SSB and IDEAindex improving our ability to simulate R from SRR Ricker and GAMformulations. The best model for R was obtained from the negative effectof SSB, inﬂuenced by NAO index, and IDEA index during 1980-1995.For red shrimp, a positive effect of the global MO index on its abundanceand SSB was detected. Results also suggest that density-dependent andenvironmental factors affect R of this species. A direct positive effect ofSSB and negative effect of IDEA index on R have been detected, whileMO index also affects R, but indirectly through SSB.The results indicate that macro and meso-scale climate regimes can inﬂu-ence the population dynamics of hake and red shrimp around the BalearicIslands. Specially for recruitment, which seems to be enhanced duringlow NAO and IDEA indices periods, when colder-than-normal winters,producing high generation of cold Winter Intermediate Waters in the Gulfof Lions, which ﬂow southwards and reach the Balearic Islands channelsin spring, increasing the productivity in the area. This oceanographicscenario could also be favourable to the distribution of hake on the ﬁshinggrounds where trawl ﬂeet target to this species, increasing its accessibilityto the ﬁshery. Both spawning stock and abundance of red shrimp seems tobe also enhanced by high MO index periods, which could reﬂect the majorpresence of the saline and warm Levantine Intermediate Waters (LIW) inthe study area, which extends over the ﬁshing grounds of this species.These proposed interactions between external and internal variables onhake and red shrimp populations can be useful to assess and manage theseimportant demersal resources in the Balearic Islands: (i) allowing theidentiﬁcation of reliable environmental indices and their integration intostock assessment models; (ii) and enhancing our ability for recruitmentforecasting.Fig. 1. Data series of environmental variables (NAO, MO and IDEAindices, represented by three years running averaged) and population dy-namics (CPUE: catch per unit effort; R: recruitment; SSB: spawning stockbiomass) of hake and red shrimp in the Balearic Islands used in this study.AcknowledgementsThe IDEA project has been funded by the Spanish Ministry of Educationand Science (Plan Nacional I+D+i 2000-2003, REN2002-04535-C02-02/MAR).ReferenceMarcos M., Monserrat S., López-Jurado J.L., Massutí E., Oliver P. andMoranta J., (submitted). A mesoscale index to describe The inﬂuenceof oceanographic scenarios on the population dynamics of demersal re-sources in the western Mediterranean: hypothesis for hake and red shrimpoff Balearic Islands. Communication to the Physics and Climate of theOceans Committee of the 38th CIESM Congress.538                                    

The influence of oceanographic scenarios on the population dynamics of demersal resources in the Western Mediterranean: Hypotesis for hake and red shrimp off Balearic Islands

Massutí, Enric

Monserrat, Sebastià

Oliver, Pere

Moranta, Joan

López-Jurado, José Luis

Marcos, Marta

Hidalgo, Manuel

Guijarro, Beatriz

Carbonell, Ana

Digital.CSIC

http://www.repositorio.ieo.es/e-ieo/bitstream/10508/5668/1/CIESM_Congress_2007.pdf

The influence of oceanographic scenarios on the population dynamics of demersal resources in the Western Mediterranean: Hypotesis for hake and red shrimp off Balearic Islands

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