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Fish production integrates changes in biomass from growth, reproduction, and mortality, and is a useful indicator for fisheries management. However, calculation of fish production has been limited by the intensive requirements for data on abundance, biomass, age structure, and vital rates, and so it is uncommon to find estimates of fish production for wetlands. We developed an approach to directly estimate production that is suitable for data-limited systems: a continuous time model of production describing individual growth over short time intervals with continuous time models of abundance and biomass over longer timescales. We applied this model for 18 Great Lakes coastal wetlands (GLCWs) on Lake Ontario, including Big Island Wetland (BIW). In BIW, most species were dominated in abundance and biomass by younger cohorts and, as a result, these young, fast-growing individuals contributed disproportionately to fish production. In total, BIW produced 336.1 kg·ha·year of fish and the other 17 neighbouring ranged between 447.7 and 1119.9 kg·ha·year. These are some of the first estimates of fish production for GLCWs, highlighting their value for managing Great Lakes fisheries. [ABSTRACT FROM AUTHOR]

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Despite management efforts, like the implementation of escape panels and openings, unwanted catch remains a challenge in demersal trawl fisheries. Studies report that selectivity in escape panels and openings can be low. We explore the selective potential of a large escape opening placed at the aft of the trawl. We then examine if adding a dark tunnel behind the escape opening can increase the escape efficiency of fish by triggering a station-holding behaviour. Our results showed limited escapement through the large escape opening; however, significant for narrow length ranges of some species. Adding the dark tunnel significantly increased the escapement for all analysed species, with escapement up to 70% (40%–83%) and 63% (8%–93%) for roundfish and flatfish, respectively. As target species, a loss of crustaceans up to 85% (60%–96%) highlighted the importance of optimising the integration of the dark tunnel in demersal trawls. Providing the dark tunnel is integrated correctly, our results suggest that currently implemented escape panels and openings with low selective efficiency could be substantially improved by simple means like the dark tunnel. [ABSTRACT FROM AUTHOR]

The principle of catch-and-release (C&R) angling is to conserve fish populations while allowing the socioeconomic benefits associated with recreational angling to continue, even at low-stock abundances. We explored how angling-associated parental stress close to spawning could influence early development of the next generation. Wild Atlantic salmon, Salmo salar, were captured on the river Blackwater, N. Scotland, during their spawning migration and exposed to different disturbance protocols intended to simulate C&R angling. Experimental fish were mated with non-experimental fish and their offspring were monitored. Mortality was higher in offspring whose parents were air-exposed. Embryos from stressed parents had smaller yolk sacs compared to controls and offspring from air-exposed parents were shorter at first feeding. Most effects were of similar magnitude regardless of the stressed parent's sex and indicated that C&R angling of Atlantic salmon close to spawning could adversely influence the offspring development. These results suggest that consideration must be given to excluding spawning periods from fishing seasons, and highlight the importance of avoiding air exposure for captured fish, as indicated by best practice guidelines. [ABSTRACT FROM AUTHOR]