ICES Journal of Marine Science: Journal du Conseil

Ottersen, Geir

doi: 10.1093/icesjms/fsq099pmid: N/A

Ottersen, G. 2010. A digital temperature atlas for the Norwegian Sea. ICES Journal of Marine Science, 67: 15251537.The first digital temperature atlas for the Norwegian Sea (Nordic Seas/GIN Sea) is described and examples of applications given. The atlas is intended mainly to make historical temperature values available to fisheries oceanographers, fisheries biologists, and stock assessment scientists in a structured, uniform format. It should also be of interest to physical oceanographers, climate researchers, and numerical modellers, and will be of relevance to remote-sensing analyses. The atlas, made freely available for scientific non-commercial purposes, is based on interpolation from 59 496 mainly Norwegian, Faroese, and Icelandic hydrographic stations. It consists of gridded temperature fields for the area 20W20E 6080N, with a spatial resolution of 1/2 longitude by 1/3 latitude. It covers the quarters JanuaryMarch, AprilJune, JulySeptember, and OctoberDecember for each year from 1990 to 2007 at 28 depth levels from 0 to 500 m. Two versions of the atlas were produced, one based solely on actual data and one where cells with missing values were filled from World Ocean Atlas 05 climatology. Suggested applications include the mapping of horizontal fields and vertical sections, initiation or verification of numerical models, comparisons with SST values from remote sensing, calculations within any chosen latitudelongitudedepth box, and the estimation of the ambient temperatures fish experience when the atlas is used in conjunction with information on fish distribution.

O'Neill, Michael F.; Campbell, Alexander B.; Brown, Ian W.; Johnstone, Ron

doi: 10.1093/icesjms/fsq095pmid: N/A

O'Neill, M. F., Campbell, A. B., Brown, I. W., and Johnstone, R. 2010. Using catch rate data for simple cost-effective quota setting in the Australian spanner crab (Ranina ranina) fishery. ICES Journal of Marine Science, 67: 15381552.For many fisheries, there is a need to develop appropriate indicators, methodologies, and rules for sustainably harvesting marine resources. Complexities of scientific and financial factors often prevent addressing these, but new methodologies offer significant improvements on current and historical approaches. The Australian spanner crab fishery is used to demonstrate this. Between 1999 and 2006, an empirical management procedure using linear regression of fishery catch rates was used to set the annual total allowable catch (quota). A 6-year increasing trend in catch rates revealed shortcomings in the methodology, with a 68 increase in quota calculated for the 2007 fishing year. This large quota increase was prevented by management decision rules. A revised empirical management procedure was developed subsequently, and it achieved a better balance between responsiveness and stability. Simulations identified precautionary harvest and catch rate baselines to set quotas that ensured sustainable crab biomass and favourable performance for management and industry. The management procedure was simple to follow, cost-effective, robust to strong trends and changes in catch rates, and adaptable for use in many fisheries. Application of such tried-and-tested empirical systems will allow improved management of both data-limited and data-rich fisheries.

Zwolinski, Juan P.; Oliveira, Paulo B.; Quintino, Victor; Stratoudakis, Yorgos

doi: 10.1093/icesjms/fsq068pmid: N/A

Zwolinski, J. P., Oliveira, P. B., Quintino, V., and Stratoudakis, Y. 2010. Sardine potential habitat and environmental forcing off western Portugal. ICES Journal of Marine Science, 67: 15531564.Relationships between sardine (Sardina pilchardus) distribution and the environment off western Portugal were explored using data from seven acoustic surveys (spring and autumn of 2000, 2001, 2005, and spring 2006). Four environmental variables (salinity, temperature, chlorophyll a, and acoustic epipelagic backscatter other than fish) were related to the acoustic presence and density of sardine. Univariate quotient analysis revealed sardine preferences for waters with high chlorophyll a content, low temperature and salinity, and low acoustic epipelagic backscatter. Generalized additive models depicted significant relationships between the environment and sardine presence but not with sardine density. Maps of sardine potential habitat (SPH) built upon the presence/absence models revealed a clear seasonal effect in the across-bathymetry and alongshelf extension of SPH off western Portugal. During autumn, SPH covered a large part of the northern Portuguese continental shelf but was almost absent from the southern region, whereas in spring SPH extended farther south but was reduced to a narrow band of shallow coastal waters in the north. This seasonal pattern agrees with the spatio-temporal variation of primary production and oceanic circulation described for the western Iberian shelf.

Solari, A. P.; Santamara, M. T. G.; Borges, M. F.; Santos, A. M. P.; Mendes, H.; Balgueras, E.; Daz Cordero, J. A.; Castro, J. J.; Bas, C.

doi: 10.1093/icesjms/fsq107pmid: N/A

Solari, A. P., Santamara, M. T. G., Borges, M. F., Santos, A. M. P., Mendes, H., Balgueras, E., Daz Cordero, J. A., Castro, J. J., and Bas, C. 2010. On the dynamics of Sardina pilchardus: orbits of stability and environmental forcing. ICES Journal of Marine Science, 67: 15651573.The dynamics of Sardina pilchardus in Iberian upwelling are examined. Spawning-stock biomass (SSB), recruitment (R), and production (R/SSB) data for the years 19782006 are analysed in relation to the upwelling index (UPW) and sea surface temperature (SST). The population oscillates in two relatively stable orbits (identified by multiresolution decomposition of the recruitment series) because the external forcing (UPW and SST) are the inverse of each other and the synchrony is lost between the two external variables, R and R/SSB as they shift towards steep, negative (depensatory) trends. Such mechanics may have induced recruitment failures and significant decreases in abundance of Iberian sardine. The relationships are assumed to validate a complex and dynamic continuum (multiple orbits of stability) and an alternative variable-carrying-capacity population model. Radial systems with two orbits of stability are proposed for the R/SSB and S/SSB (where S is the stock size) relationships. Results are discussed in relation to classical and alternative SR models to address stock rehabilitation and fishing mortality issues as the population shifts towards low recruitment and abundance, and critical factors to consider in developing exploitation strategies for systems with multiple orbits of stability are discussed.

Tugores, M. Pilar; Iglesias, Magdalena; Daz, Nria; Oate, Dolores; Miquel, Joan; Girldez, Ana

doi: 10.1093/icesjms/fsq057pmid: N/A

Tugores, M. P., Iglesias, M., Daz, N., Oate, D., Miquel, J., and Girldez, A. 2010. Latitudinal and interannual distribution of the European anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the western Mediterranean, and sampling uncertainty in abundance estimates. ICES Journal of Marine Science, 67: 15741586.On the Spanish Mediterranean continental shelf, late-autumn echo-integration acoustic surveys have been performed annually since the 1990s. The surveys coincide with the recruitment season of anchovy (Engraulis encrasicolus) and the start of the spawning season of sardine (Sardina pilchardus), and they provide estimates of stock size for the main fisheries in the area. Latitudinal distribution of the abundance of the two species from 2003 till 2006 is evaluated, and transitive geostatistical techniques applied to estimate the sampling uncertainty of the overall abundance estimate. The anchovy stock was found mainly in areas influenced by river run-off, in well-known anchovy spawning areas, suggesting that anchovy remained on their spawning grounds until late autumn or that survival was higher in these regions of enhanced productivity. By the time of the surveys, sardine were already occupying their spawning grounds over the continental shelf. The precision of the abundance estimates was generally high. The few cases of low precision were re-examined and found to stem most probably from processing errors, so the re-examination has contributed to an improvement in the accuracy of the estimates. The greater precision obtained in the southern subarea suggested a greater homogeneity in the spatial distribution of both species.

Ljunggren, Lars; Sandstrm, Alfred; Bergstrm, Ulf; Mattila, Johanna; Lappalainen, Antti; Johansson, Gustav; Sundblad, Gran; Casini, Michele; Kaljuste, Olavi; Eriksson, Britas Klemens

doi: 10.1093/icesjms/fsq109

Serra-Pereira, Brbara; Farias, Ins; Moura, Teresa; Gordo, Leonel Serrano; Santos, Miguel; Figueiredo, Ivone

doi: 10.1093/icesjms/fsq056pmid: N/A

Serra-Pereira, B., Farias, I., Moura, T., Gordo, L. S., Santos, M., and Figueiredo, I. 2010. Morphometric ratios of six commercially landed species of skate from the Portuguese continental shelf, and their utility for identification. ICES Journal of Marine Science, 67: 15961603.European skate landings have traditionally been reported under a generic landing category, because of problems with species identification. To address this data deficiency, the ICES Working Group on Elasmobranch Fishes compiled conversion factors, including the relationships between different body measurements, for the main elasmobranch species. Size conversion factors for six common NE Atlantic skate species, Leucoraja naevus, Raja brachyura, R. clavata, R. miraletus, R. montagui, and R. undulata are compiled, and the capability of morphometric data to assist species discrimination is evaluated, highlighting the case of similar species such as R. brachyura and R. montagui. The estimated size conversion factors displayed some variability between areas and sexes for most species, the allometric relationship between weight and total length did not differ significantly between sexes, and some morphometric ratios proved adequate in discriminating between rajid species (misclassification error 0.12). Leucoraja naevus was fully discriminated from the remaining species. Species with a similar dorsal colour, e.g. R. brachyura and R. montagui, showed good discrimination based on their morphometry, with just 611 misclassification between the two.

Punzn, Antonio; Hernndez, Carmen; Abad, Esther; Castro, Jos; Prez, Nelida; Trujillo, Valentn

doi: 10.1093/icesjms/fsq085pmid: N/A

Punzn, A., Hernndez, C., Abad, E., Castro, J., Prez, N., and Trujillo, V. 2010. Spanish otter trawl fisheries in the Cantabrian Sea. ICES Journal of Marine Science 67: 16041616A non-hierarchical classification technique (clustering large applications, CLARA) was used to identify four fishing tactics of Spanish otter trawlers in the Cantabrian Sea (ICES Division VIIIc) from 1983 to 2004: mixed fishing, blue whiting fishing, horse mackerel fishing, and mackerel fishing. There were no significant differences in the fishing tactics employed by two trawl fleets identified using a non-hierarchical classification technique (partition around medoids). There was, however, a decline in the use of the blue whiting fishing tactic from 2000 on, perhaps as a result of competition with pairtrawls, a gear whose main target species is blue whiting. There was an increase in the number of trips using the mackerel fishing tactic from 1996, a change possibly caused by improved market conditions. Between 2000 and 2004, the fleets had two distinct behaviour patterns, identified depending on the area in which they operated. The study area could therefore be subdivided into two areas based on the prevalence of the fishing tactic followed. The horse mackerel fishing tactic was more commonly used in the west, and the mixed fishing tactic in the east.

Cadrin, Steven X.; Bernreuther, Matthias; Danelsdttir, Anna Kristn; Hjrleifsson, Einar; Johansen, Torild; Kerr, Lisa; Kristinsson, Kristjan; Mariani, Stefano; Nedreaas, Kjell; Pampoulie, Christophe; Planque, Benjamin; Reinert, Jkup; Saborido-Rey, Fran; Sigursson, Thorsteinn;

Kerr, Lisa A.; Cadrin, Steven X.; Secor, Dave H.

doi: 10.1093/icesjms/fsq053pmid: N/A

Kerr, L. A., Cadrin, S. X., and Secor, D. H. 2010. Simulation modelling as a tool for examining the consequences of spatial structure and connectivity on local and regional population dynamics. ICES Journal of Marine Science, 67: 16311639.An understanding of the mechanisms underlying population persistence makes fisheries management more effective. A model framework is described, which can test hypotheses about spatial structure and connectivity within and between populations and their influence on the productivity (spawning-stock biomass, SSB), stability (variation in SSB), resilience (time to rebuild SSB after environmental disturbance), and sustainability (maximum sustainable fishing mortality and yield) of systems. The general model consists of linked age-structured submodels that incorporate the unique demographics and dynamics of population components, along with the degree and type of connectivity between them. The flexibility of this framework is illustrated with three case studies examining (i) spatial structure within a population of white perch, (ii) different types and degrees of connectivity between populations of Atlantic herring, and (iii) spatial heterogeneity and connectivity within a stock of Atlantic cod. System variance is reduced by abundant, stable population components, and the asynchronous responses of those components. Components with high productivity contributed disproportionately to the resilience of systems. Increased synchrony of component responses to environmental forcing decreased the stability of the overall system. Simulation modelling is a useful approach to evaluate the consequences of spatial structure and connectivity, and can be used to understand better the productivity and dynamics of local and regional populations.