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Beverton and Holt's (1957. On the dynamics of exploited fish populations. UK Ministry of Agriculture, Fisheries and Food. Fisheries Investigations, 2: 533 pp.) monograph contributed a widely used stock–recruitment relationship (BH-SRR) to fisheries science. However, because of variation around a presumed relationship between spawning biomass and recruits, the BH-SRR is often considered inadequate and approached merely as a curve-fitting exercise. The commonly used and simplified version of the BH-SRR has eclipsed the fact that in their classic monograph, the derivation accounted for mechanistic recruitment processes, including multi-stage recruitment with explicit cohort-dependent and -independent mortality terms that represent competition between recruits and extrinsic, cohort-independent factors such as the environment or predation as two independent sources of mortality. The original BH-SRR allows one to recreate recruitment patterns that correspond to observed ones. Doing so shows that variation in density-independent mortality increases the probability of overlooking an underlying stock–recruitment relationship. Intermediate coefficients of variation in mortality (75–100%) are sufficient to mask stock–recruitment relationships and recreate recruitment time series most similar to empirical data. This underlines the importance of variation in survival for recruitment and that Beverton and Holt's work still provides a fundamental and useful tool to model the dynamics of populations. [ABSTRACT FROM AUTHOR]

Following from similar initiatives worldwide, the U.K.'s Fisheries Science Partnership ( FSP) was established in 2003 to provide the fishing industry with opportunities to propose and participate in scientific studies in collaboration with fishery scientists. Key concepts were that most of the available funding would support industry participation, that industry, not scientists, would come up with the ideas for projects, and that commercial fishing vessels and fishing methods would be used to address specific concerns of the fishing industry in a scientifically controlled manner. Nearly 100 projects had been commissioned by March 2012, covering annual time-series surveys of stocks subject to traditional assessment, and ad hoc projects on, e.g. gear selectivity, discard survival, tagging and migration and fishery development. The extent to which the results of the projects have been used by stakeholders, fishery scientists and fishery managers at a national and E.U. level is evaluated, along with the degree of industry interest and involvement, and reasons are identified for successes or failures in the uptake of the results into management and policy. Finally, the question is posed whether the programme has been successful in improving the engagement of the fishing community in the science-management process and in fostering communication and greater trust between fishers, scientists and managers. [ABSTRACT FROM AUTHOR]

Comparative assessments of population mean growth rates in length remain important aspects of stock assessment in river fisheries. To facilitate these assessments, for 15 fish species encountered in UK rivers reference data are provided on their expected lengths at age, maximum theoretical lengths ( L∞), growth coefficient ( K) and instantaneous mortality rate ( Z). These data are also transferable to fish populations outside of the UK that experience a similar growth season (approximately April to October, mean water temperatures 12–22°C). Considerable plasticity was observed in the growth of all species examined, with length at age values revealing growth rates from very slow to very fast. Populations considered fast growing against reference data were coincident with a relatively low ultimate length, a high growth coefficient and a high instantaneous mortality rate, suggesting a trade-off exists between growth rate, ultimate length and life span. [ABSTRACT FROM AUTHOR]

The topmouth gudgeon ( Pseudorasbora parva) is a species that is becoming invasive in UK waters. Few biological studies have been completed on the species in this extended range, resulting in sparse information in some aspects of their invasion biology. Regarding length–weight relationships, this is remedied in this study by providing data for 10 lake populations in the UK. Using fish length range 2.5–11.8 cm, values of a and b in the length–weight equation are provided. Values of b ranged between 2.76 and 3.32. Across all lakes, the relationship was W = 0.011L3.03, with weight in grams and length (fork) in cm. [ABSTRACT FROM AUTHOR]

• First molecular detection of Bonamia exitiosa in the Solent and second in the UK. • 380 samples analysed with the pathogen observed in mature and larval O. edulis. • Larvae shown to be positive were collected from brooding adults that were negative. • Larvae should be considered as a possible source of B. exitiosa infection. • Larvae should also be considered for disease resistance selection. The haplosporidian parasite Bonamia exitiosa was detected using PCR in four adult and six larval brood samples of the European flat oyster Ostrea edulis from the Solent, UK. This represents the second reported detection of this parasite along the south coast of England. Adult oysters were collected and preserved from seabed populations or restoration broodstock cages between 2015 and 2018. The larvae within brooding adults sampled during 2017 and 2018 were also preserved. Molecular analysis of all samples was performed in 2019. The DNA of B. exitiosa was confirmed to be present within the gill tissue of one oyster within the Portsmouth wild fishery seabed population (n = 48), sampled in November 2015; the congeneric parasite Bonamia ostreae was not detected in this individual. This is the earliest record of B. exitiosa in the Solent. Concurrent presence of both B. ostreae and B. exitiosa , determined by DNA presence, was confirmed in the gill and heart tissue of three mature individuals from broodstock cages sampled in October 2017 (n = 99), two from a location on the River Hamble and one from the Camber Dock in Portsmouth Harbour. B. exitiosa was not detected in the November 2018 broodstock populations. A total of six larval broods were positive for B. exitiosa , with five also positive for B. ostreae. None of the brooding adults were positive for B. exitiosa suggesting that horizontal transmission from the surrounding environment to the brooding larvae is occurring. Further sampling of broodstock populations conducted by the Fish Health Inspectorate at the Centre for Environment, Fisheries and Aquaculture Science in June 2019 did not detect infection of O. edulis by B. exitiosa. These findings together suggest that the pathogen has not currently established in the area. [ABSTRACT FROM AUTHOR]

• Evaluation of shellfish domoic acid occurrence from ten-year monitoring programme from Great Britain. • Frequency of toxin events increasing during this period. • Majority of toxic events associated with Pseudo-nitzschia blooms. • Shellfish toxicity not directly correlated with cell abundance. As the official control laboratory for marine biotoxins within Great Britain, the Centre for Environment, Fisheries and Aquaculture Science, in conjunction with the Scottish Association for Marine Science, has amassed a decade's worth of data regarding the prevalence of the toxins associated with Amnesic Shellfish Poisoning within British waters. This monitoring involves quantitative HPLC-UV analysis of shellfish domoic acid concentration, the causative toxin for Amnesic Shellfish Poisoning, and water monitoring for Pseudo-nitzschia spp., the phytoplankton genus that produces domoic acid. The data obtained since 2008 indicate that whilst the occurrence of domoic acid in shellfish was generally below the maximum permitted limit of 20 mg/kg, there were a number of toxic episodes that breached this limit. The data showed an increase in the frequency of both domoic acid occurrence and toxic events, although there was considerable annual variability in intensity and geographical location of toxic episodes. A particularly notable increase in domoic acid occurrence in England was observed during 2014. Comparison of Scottish toxin data and Pseudo-nitzschia cell densities during this ten-year period revealed a complex relationship between the two measurements. Whilst the majority of events were associated with blooms, absolute cell densities of Pseudo-nitzschia did not correlate with domoic acid concentrations in shellfish tissue. This is believed to be partly due to the presence of a number of different Pseudo-nitzschia species in the water that can exhibit variable toxin production. These data highlight the requirement for tissue monitoring as part of an effective monitoring programme to protect the consumer, as well as the benefit of more detailed taxonomic discrimination of the Pseudo-nitzschia genus to allow greater accuracy in the prediction of shellfish toxicity. [ABSTRACT FROM AUTHOR]

The article reports developments within the Institute of Fisheries Management in Great Britain in 1972. On September 20-22, the Institute will be represented at the International Symposium on the management, biology and survival of Atlantic salmon in New Brunswick, Canada. The number of registered students for the course on fisheries offered by the Institute in the Northern Branch had increased. Meetings held by the Institute's branch in South Wales had been successful.