ICES Journal of Marine Science: Journal du Conseil

Broadhurst, Matt K.; Millar, Russell B.; Uhlmann, Sebastian S.

doi: 10.1093/icesjms/fsp155pmid: N/A

Broadhurst, M. K., Millar, R. B., and Uhlmann, S. S. 2009. Using a double codend to reduce discard mortality. ICES Journal of Marine Science, 66: 20772081.Traditional technical strategies for mitigating collateral fishing mortality have involved improving gear selectivity (to reduce bycatch) and, more recently, concomitant changes to onboard handling procedures to reduce some of the negative impacts to the remaining discards. A less common approach is to modify gears physically to minimize deleterious catching mechanisms and subsequent mortalities during fishing. This study aimed to investigate the utility of the latter category of modifications for penaeid trawls by separating a codend into two compartments (termed a double codend) to alleviate interactions between catches. Compared with a conventional design, the double codend significantly reduced the immediate (from 17.1 to 13.8) and short-term (22.5 to 17.1) mortalities of discarded juvenile school prawns (Metapenaeus macleayi). The effectiveness of the double codend remained independent of other factors known to affect the fate of discarded juvenile M. macleayi, including cloud cover and, owing to minimal variability, the weight of the total catch. However, irrespective of the codend configuration, overall mortalities were also positively correlated with the quantity of jellyfish. We conclude that when combined with modifications to improve selectivity and appropriate onboard handling strategies, compartmentalizing codend catches could cumulatively reduce unaccounted fishing mortality.

Harris, Peter T.; Heap, Andrew D.; Anderson, Tara J.; Brooke, Brendan

doi: 10.1093/icesjms/fsp207pmid: N/A

Harris, P. T., Heap, A. D., Anderson, T. J., and Brooke, B. 2009. Comment on: Williams et al. (2009) Australia's deep-water reserve network: implications of false homogeneity for classifying abiotic surrogates of biodiversity. ICES Journal of Marine Science, 66: 214224. ICES Journal of Marine Science, 66: 20822085.Williams et al. (2009) report on new multibeam sonar bathymetry and underwater video data collected from submarine canyons and seamounts on Australia's southeast continental margin to investigate the degree to which geomorphic features act as surrogates for benthic megafaunal biodiversity (p. 214). The authors describe what they view as deficiencies in the design of the Marine Protected Areas (MPAs) in the southeast region of Australia, in which geomorphology information was employed as a surrogate to infer regional-scale patterns of benthic biodiversity. This comment is designed to support and underscore the importance of evaluating MPA designs and the validity of using abiotic surrogates such as geomorphology to infer biodiversity patterns, and also seeks to clarify some of the discrepancies in geomorphic terminologies and approaches used between the original study and the Williams et al. (2009) evaluation. It is our opinion that the MPA design criteria used by the Australian Government are incorrectly reported by Williams et al. (2009). In particular, we emphasize the necessity for consistent terminology and approaches when undertaking comparative analyses of geomorphic features. We show that the MPA selection criteria used by the Australian Government addressed the issues of false homogeneity described by Williams et al. (2009), but that final placement of MPAs was based on additional stakeholder considerations. Finally, we argue that although the Williams et al. (2009) study provides valuable information on biological distributions within seamounts and canyons, the hypothesis that geomorphic features (particularly seamounts and submarine canyons) are surrogates for benthic biodiversity is not tested explicitly by their study.

Williams, Alan; Bax, Nicholas J.; Kloser, Rudy J.

doi: 10.1093/icesjms/fsp212pmid: N/A

Williams, A., Bax, N. J., and Kloser, R. J. 2009. Remarks on Comment on: Williams et al. (2009) Australia's deep-water reserve network: implications of false homogeneity for classifying abiotic surrogates of biodiversity, ICES Journal of Marine Science, 66: 214224 by Peter T. Harris, Andrew D. Heap, Tara J. Anderson, and Brendan Brooke. ICES Journal of Marine Science, 66: 20862088.Commitment by many nations at the 2002 World Summit on Sustainable Development to complete national networks of Marine Protected Areas (MPAs) by 2012 focused attention on MPA design and implementation, especially for the deep waters that make up the majority of many national EZs. Further, there is a focus on conservation in the High Seas through the Convention on Biological Biodiversity and the FAO, e.g. for seamounts and other vulnerable benthic habitats. Any manuscript that raises basic issues on one identified area for conservation is therefore a prospectively useful addition to the international debate. The Comment by Harris et al. (2009) on a paper authored by myself and colleagues (Williams et al., 2009) is a potentially useful contribution. The authors provide data, examples, and insights into aspects of the design and planning process for Australia's SE network of reserves. Here, we address the main question of how geological descriptions can be used or modified to provide the most information on marine biodiversity patterns for use in conservation planningin the context of the major points raised by Harris et al. (2009).

Schipper, Cor A.; Lahr, Joost; van den Brink, Paul J.; George, Steve G.; Hansen, Peter-Diedrich; da Silva de Assis, Helena C.; van der Oost, Ron; Thain, John E.; Livingstone, Dave; Mitchelmore, Carys; van Schooten, Frederik-Jan; Ariese, Freek; Murk, Albertinka J.; Grinwis, Guy C. M.;

Bekkby, Trine; Rinde, Eli; Erikstad, Lars; Bakkestuen, Vegar

doi: 10.1093/icesjms/fsp195pmid: N/A

Bekkby, T., Rinde, E., Erikstad, L., and Bakkestuen, V. 2009. Spatial predictive distribution modelling of the kelp species Laminaria hyperborea. ICES Journal of Marine Science, 66: 21062115.The kelp species Laminaria hyperborea constitutes highly productive kelp forest systems hosting a broad diversity of species and providing the basis for commercial kelp harvesting and, through its productivity, the fishing industry. Spatial planning and management of this important habitat and resource needs to be based on distribution maps and detailed knowledge of the main factors influencing the distribution. However, in countries with a long and complex coastline, such as Norway, detailed mapping is practically and economically difficult. Consequently, alternative methods are required. Based on modelled and field-measured geophysical variables and presence/absence data of L. hyperborea, a spatial predictive probability model for kelp distribution is developed. The influence of depth, slope, terrain curvature, light exposure, wave exposure, and current speed on the distribution of L. hyperborea are modelled using a generalized additive model. Using the Akaike Information Criterion, we found that the most important geophysical factors explaining the distribution of kelp were depth, terrain curvature, and wave and light exposure. The resulting predictive model was very reliable, showing good ability to predict the presence and absence of kelp.

Wagler, H.; Berghahn, R.; Vorberg, R.

doi: 10.1093/icesjms/fsp201pmid: N/A

Wagler, H., Berghahn, R., and Vorberg, R. 2009. The fishery for whiteweed, Sertularia cupressina (Cnidaria, Hydrozoa), in the Wadden Sea, Germany: history and anthropogenic effects. ICES Journal of Marine Science, 66: 21162120.The whiteweed fishery in the German Wadden Sea did not close as a consequence of the loss of whiteweed beds, but rather because of declining markets. To this day, neither the assumed disappearance of whiteweed beds nor the assumed decrease in whiteweed abundance has been substantiated. Even if such a decrease were to be demonstrated, the causes for the decline would more likely have been eutrophication and anthropogenic changes in the hydrodynamics of the Wadden Sea than the activities of the shrimp and mussel fisheries or the former whiteweed fishery.

Gaspar, M. B.; Carvalho, S.; Constantino, R.; Tata-Regala, J.; Crdia, J.; Monteiro, C. C.

doi: 10.1093/icesjms/fsp202pmid: N/A

Gaspar, M. B., Carvalho, S., Constantino, R., Tata-Regala, J., Crdia, J., and Monteiro, C. C. 2009. Can we infer dredge fishing effort from macrobenthic community structure? ICES Journal of Marine Science, 66: 21212132.The effects of commercial fishing effort (FE) on macrobenthic community structure were analysed in geographically related fishing grounds separated into three groups: non-exploited (NE), moderately exploited (ME), and highly exploited (HE). Number of species, abundance, Margalef species richness, and ShannonWiener diversity were significantly higher in NE than in exploited areas. The first two were also significantly higher in HE than in ME areas. Measures of taxonomic diversity differed depending on whether annelids, molluscs, and crustaceans were combined or analysed separately. Crustaceans seemed to be the most vulnerable to bivalve dredging because significantly lower values were observed for them in the HE areas than in the ME and NE areas for this group. Although the samples were taken at the end of the closed season, macrobenthic communities still showed differences that may be related to FE, especially in trophic structure. Carnivory was particularly dominant in HE areas. The ratio of carnivory to filter-feeding was significantly correlated with FE, with higher values being observed in HE areas and lower values in NE areas.

Gumundsson, Kristinn; Heath, Mike R.; Clarke, Elizabeth D.

doi: 10.1093/icesjms/fsp208pmid: N/A

Gumundsson, K., Heath, M. R., and Clarke, E. D. 2009. Average seasonal changes in chlorophyll a in Icelandic waters. ICES Journal of Marine Science, 66: 21332140.The standard algorithms used to derive sea surface chlorophyll a concentration from remotely sensed ocean colour data are based almost entirely on the measurements of surface water samples collected in open sea (case 1) waters which cover 60 of the worlds oceans, where strong correlations between reflectance and chlorophyll concentration have been found. However, satellite chlorophyll data for waters outside the defined case 1 areas, but derived using standard calibrations, are frequently used without reference to local in situ measurements and despite well-known factors likely to lead to inaccuracy. In Icelandic waters, multiannual averages of 8-d composites of SeaWiFS chlorophyll concentration accounted for just 20 of the variance in a multiannual dataset of in situ chlorophyll a measurements. Nevertheless, applying penalized regression spline methodology to model the spatial and temporal patterns of in situ measurements, using satellite chlorophyll as one of the predictor variables, improved the correlation considerably. Day number, representing seasonal variation, accounted for substantial deviation between SeaWiFS and in situ estimates of surface chlorophyll. The final model, using bottom depth and bearing to the sampling location as well as the two variables mentioned above, explained 49 of the variance in the fitting dataset.

Fast, Mark D.; Sokolowski, Mark S.; Dunton, Keith J.; Bowser, Paul R.

doi: 10.1093/icesjms/fsp186pmid: N/A

Fast, M. D., Sokolowski, M. S., Dunton, K. J., and Bowser, P. R. 2009. Dichelesthium oblongum (Copepoda: Dichelesthiidae) infestation in wild-caught Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus. ICES Journal of Marine Science, 66: 21412147.Atlantic sturgeon were sampled in autumn 2007 and 2008 along the New York Bight. The fish were examined for the presence of external parasites, and blood, fin, and opercula biopsies were collected for subsequent serum analysis and histopathological evaluation. Dichelesthium oblongum, a parasitic copepod, was observed on 93 of the sturgeon sampled (77 out of 83) between Rockaway and Jones Beaches, NY, and Sandy Hook, NJ. During the course of the examinations, grossly visible lesions associated with the attachment and feeding of juvenile stages of D. oblongum were noted on the operculum, pectoral, dorsal, and anal fins of infested fish. Significant differences were observed between the level of infestation and serum chemistry across sampling sites, such that the most heavily infested fish were caught off Jones Beach (15.8 2.79 lice fish1), higher infestations than at Rockaway Beach (8.86 0.89 lice fish1) and Sandy Hook (5.31 1.40 lice fish1). Animals from Jones Beach also indicated ion loading (i.e. sodium, calcium, and magnesium), possibly as a result of stress or water loss through D. oblongum infestation compromising the epithelial barrier. The interaction of the environment and parasite with host life-history characteristics are discussed in terms of their ecological significance to this threatened fish species.

Hill, Simeon L.; Trathan, Philip N.; Agnew, David J.

doi: 10.1093/icesjms/fsp172pmid: N/A

Hill, S. L., Trathan, P. N., and Agnew, D. J. 2009. The risk to fishery performance associated with spatially resolved management of Antarctic krill (Euphausia superba) harvesting. ICES Journal of Marine Science, 66: 21482154.The ecosystem approach to fisheries attempts to define objectives for target species, the wider ecosystem, and critically, the fishery itself. Proposals for implementing the approach often include spatial restrictions on harvesting, so it is important to understand how these will affect fishery performance. One metric of potential performance is the probability of encountering exploitable densities of a target species at the scale of fishing operations. The probability of encountering exploitable densities of Antarctic krill, Euphausia superba, at the scale of 1 nautical mile during an acoustic survey was predicted by bathymetry and the mean krill density at the larger scale at which the fishery is managed. This suggests that the risk to fishery performance will increase if management actions relocate the fishery into deeper water. The results also suggest that ecosystem models resolved to the spatial scale of management units could usefully predict effects at the scale of fishing operations. However, correct parameterization of these models will require better characterization of threshold densities for efficient exploitation. Finally, the distribution of catch and fishing effort over an entire fishing season reflected the distribution of krill density observed during the survey.