Naturally-occurring stable isotopes as direct measures of larval feeding efficiency, nutrient incorporation and turnover

environmental conditions on stable isotope incorporation will be of broad relevance not only in terms of larval nutrition but can also more broadly inform the design and interpretation of ecological studies

Size-selective fishing of Palaemon serratus (Decapoda, Palaemonidae) in Wales, UK::implications of sexual dimorphism and reproductive biology for fisheries management and conservation

The common prawn (Palaemon serratus) supports a small-scale but economically important seasonal static-gear fishery in Cardigan Bay, Wales (UK). Due to a lack of statutory obligation and scientific evidence, the fishery has operated to date without any harvest-control rules that afford protection from overfishing. In response to fluctuations in landings and in pursuit of increased economic returns for their catch, some members of the fishing industry have adopted a size-selective harvesting regime, which we evaluate here using baseline data. Monthly samples were obtained from fishers operating out of five ports between October 2013 and May 2015 (N = 4233). All prawn were sexed, weighed and measured, whilst the fecundity of females was estimated for 273 (44%) individuals. Peak spawning occurred during the spring and females were estimated to undergo a ‘puberty moult’ at a carapace length (CL) of 7.7 mm, whilst functional maturity was estimated at a CL of 9.9 mm. The sampled population exhibited sexual dimorphism, with females attaining a greater size than males. The current harvesting regime results in a sex bias in landings as even large mature males remained under the recruitment size to the fishery, unlike the large mature females. The temporal trend in sex-ratio indicates a continual decrease in the catchability of female prawn through the fishing season; however, whether this is caused by depletion via fishing mortality or migratory behaviour is yet to be resolved. Here, we provide a comprehensive baseline evaluation of population biology and discuss the implications of our findings for fisheries management.No Full Tex

Decline in oyster populations in traditional fishing grounds; is habitat damage by static fishing gear a contributory factor in ecosystem degradation?

The territorial waters of Qatar once supported dense assemblages of the pearl oyster Pinctada radiata. The oysters settled on a patchy network of limestone platforms (hairãt) and provided a suite of ecosystem services to the surrounding marine environment. Commercially important fish species are associated with hairãt and as a result, industrial fishing with traps focused on these areas. This study has shown that heavily-fished areas are presently in a state which can be considered non-favorable to conservation while areas closed to fishing are recovering. It is probable that an increase in fishing activity using traditional Gargoor traps and grapple retrieval are responsible for the current ecological status of the hairãt. The intensity in trap fishing appears to be having a detrimental effect on species such as corals, sea grasses and oysters. The decline in the standing stock of oysters is dramatic with an estimated reduction ratio of 580:1 between 2002 and 2016. As fishing damage appears to be a significant contributor to these losses, measures such as spatial protection of productive shallow offshore habitats and restriction on fishing effort are urgently required to address the decline. Strategic oyster stock enhancement through the re-seeding of selected areas could boost the recovery of damaged hairãt as P. radiata ecosystem services return.Qatar National Research Foundation, National Priorities Research programme project NPRP-6-1680-4-02

A global review of the ecosystem services provided by bivalve aquaculture:Services of bivalve aquaculture

Bivalve shellfish aquaculture provides many benefits to society, beyond their traditional market value. This study collates the evidence available on the provisioning, regulating and cultural ecosystem services provided by the bivalve species commonly used in aquaculture. For the first time, it synthesises this evidence to provide a global assessment of the potential market and non‐market economic value of bivalve aquaculture. Bivalves are filter feeders, filtering water and particulates, creating substrates which provide habitat to act as nursery grounds for other species. Goods from provisioning services include meat, worth an estimated $23.9 billion as well as, pearls, shell and poultry grit, with oyster shell being the most important, with a global potential worth of$5.2 billion. The most important regulating services are nutrient remediation. Cultivated bivalves remove 49,000 tonnes of nitrogen and 6,000 tonnes of phosphorus, worth a potential $1.20 billion. Currently, there is little evidence on the cultural services per year of bivalve aquaculture, but we argue that these cultural values are broad ranging, although difficult to quantify. Our assessment indicates that the global, non‐food bivalve aquaculture services are worth$6.47 billion ($2.95 billion–9.99 billion) per annum. However, this is likely to be an underestimate of the true value of bivalve aquaculture as there are significant gaps in evidence of the value for a number of key services. The analysis presented here can be used to indicate the likely scale of payments for ecosystem services provided by bivalve aquaculture, prior to more detailed assessments