A preliminary examination of differential survey trends in recent years between the Canadian Spring and EU-Spain surveys for 3NO cod

Results of the EU-Spain survey in Divs. 3NO are not used as input to the current ADAPT assessment model for 3NO cod but make an interesting comparison to the Canadian Spring survey since they occur at approximately the same time of year. The two surveys exhibit differences in both abundance and biomass trends in recent years, with the EU-Spain survey results indicating some relatively strong signs of stock growth since 2007 but the Canadian spring survey showing little to no sign of stock growth. Results did not change when analyses of the Canadian survey were restricted only to strata located all or partially within the NRA. An examination of distribution plots for the two surveys suggests that a lower density of fishing sets in the NRA by the Canadian Spring survey relative to the EU-Spain survey might be at least partially responsible for the differential trends between the two survey time series in recent years. However, because the EU-Spain survey covers only a small portion of the stock area, the observed trends for this survey can not be considered indicative of the entire stock. Differences in the length distribution of the catches were also evident in some years

Data review for 3LN redfish in preparation for an updated management strategy evaluation

Data review for 3LN redfish in preparation for an updated management strategy evaluationVersión del editor

Evaluating the use of the autodiametric method for estimating fecundity of Reinhardtius hippoglossoides, a species with an unusual oocyte development strategy

The autodiametric method is a highly streamlined method for estimating fecundity of fish with determinate oocyte development pattern. Greenland halibut presents a peculiar reproductive strategy with two simultaneously cohorts one of large vitellogenic oocytes (for the current year) and another one of small vitellogenic oocytes (for the subsequent year). Results of this study showed that autodiametric method can be applied to estimate fecundity in Greenland halibut. Additionally, spatial differences in the autodiametric calibration curve were observed in the Northwest Atlantic, but did not translate into differences in fecundity at length. This is the first time that spatial differences between ACCs of the same species have been reported, what could be the result of (i) the unusual oocyte development pattern, or (ii) spatial differences in oocyte biochemistry. More research on the relative dynamics of oocyte cohorts simultaneously present in Greenland halibut ovaries and the factors (endo- or exogenous) influencing oocyte packing density could provide a better understanding of observed geographical differences.En prens

Sustainability of deep-sea fisheries

As coastal fisheries around the world have collapsed, industrial fishing has spread seaward and deeper in pursuit of the last economically attractive concentrations of fishable biomass. For a seafood-hungry world depending on the oceans' ecosystem services, it is crucial to know whether deep-sea fisheries can be sustainable.The deep sea is by far the largest but least productive part of the oceans, although in very limited places fish biomass can be very high. Most deep-sea fishes have life histories giving them far less population resilience/productivity than shallow-water fishes, and could be fished sustainably only at very low catch rates if population resilience were the sole consideration. But like old-growth trees and great whales, their biomass makes them tempting targets while their low productivity creates strong economic incentive to liquidate their populations rather than exploiting them sustainably (Clark's Law). Many deep-sea fisheries use bottom trawls, which often have high impacts on nontarget fishes (e.g., sharks) and invertebrates (e.g., corals), and can often proceed only because they receive massive government subsidies. The combination of very low target population productivity, nonselective fishing gear, economics that favor population liquidation and a very weak regulatory regime makes deep-sea fisheries unsustainable with very few exceptions. Rather, deep-sea fisheries more closely resemble mining operations that serially eliminate fishable populations and move on.Instead of mining fish from the least-suitable places on Earth, an ecologically and economically preferable strategy would be rebuilding and sustainably fishing resilient populations in the most suitable places, namely shallower and more productive marine ecosystems that are closer to markets