Pacific bonito management information document

Management of Pacific bonito in California is examined in this Management Information Document by a State-Federal team of scientists. Abundance of Pacific bonito in southern California has fallen dramatically between the 1963-1969 period and the 1974-1977 period. Since 1976 the commercia1 fleet has found few large fish in southern California, and has caught fish in the size range of 15 to 57 cm (1.2 to 4.7 pounds). This fact, coupled with the low abundance indices, point out the need for a more active management regime. To develop management measures for the California bonito fishery both a surplus yield analysis and a yield-per-recruit analysis were performed. A maximum sustained yield of 10,000 short tons was estimated for the fishery in southern California, while the whole fishery, including Baja California, has an estimated MSY of 13,000 tons. In order to achieve this level of catch, however, the stock abundance must be increased by a factor of five. Yield-per-recruit considerations suggest that a minimum size limit in the commercial fishery has two important effects. A three-pound size limit could result in a slight increase in yield-per-recruit. If the size limit is increased to 5 or 7.5 lbs, the yield-per-recruit would fall significantly. Offsetting the effect on yield-per-recruit, however, would be a substantial increase in average amount of spawning per recruit which should result in a proportional increase in recruitment. With the current depressed stock abundance both a reduced annual take and a minimum size limit on commercial catch would confer substantial benefits in the form of an increase in the future stock size. After considering seven different types of management measures, the team finds that three types -- an annual commercial catch quota, a commercial size limit, and a recreational bag limit -- appear desirable. Re-establishment of the stock in southern California was the major consideration in this evaluation because the stock is currently depressed. All segments of the fishery will benefit from a more abundant resource. The difficult issues for policy, however, concern the rate of rebuilding, the degree of risk that is acceptable, and the distribution of benefits among user groups. By judicious choice among the options discussed here, a variety of positions can be established with respect to these issues. The greater the size limit, for instance, the more benefit is provided the recreational sector while difficulties are imposed upon commercial fishermen. The higher the quotas adopted, the slower the stock rebuilding and the greater the risk of continued stock depletion. A final reconciliation of the management options involves social, political and legal considerations which must be thoroughly incorporated by decision-makers before adoption of a management plan. (93pp.

Considerations for management strategy evaluation for small pelagic fishes

Management strategy evaluation (MSE) is the state-of-the-art approach for testing and comparing management strategies in a way that accounts for multiple sources of uncertainty (e.g. monitoring, estimation, and implementation). Management strategy evaluation can help identify management strategies that are robust to uncertainty about the life history of the target species and its relationship to other species in the food web. Small pelagic fish (e.g. anchovy, herring and sardine) fulfil an important ecological role in marine food webs and present challenges to the use of MSE and other simulation-based evaluation approaches. This is due to considerable stochastic variation in their ecology and life history, which leads to substantial observation and process uncertainty. Here, we summarize the current state of MSE for small pelagic fishes worldwide. We leverage expert input from ecologists and modellers to draw attention to sources of process and observation uncertainty for small pelagic species, providing examples from geographical regions where these species are ecologically, economically and culturally important. Temporal variation in recruitment and other life-history rates, spatial structure and movement, and species interactions are key considerations for small pelagic fishes. We discuss tools for building these into the MSE process, with examples from existing fisheries. We argue that model complexity should be informed by management priorities and whether ecosystem information will be used to generate dynamics or to inform reference points. We recommend that our list of considerations be used in the initial phases of the MSE process for small pelagic fishes or to build complexity on existing single-species models.publishedVersio

Substance misuse, psychiatric disorder and parental relationships in patients attending a student health service

The mental health of students is a subject of growing concern. There are limited data on the prevalence of mental disorder in the student population and its relationship to previously noted high levels of drug and alcohol use is unknown. Although there is a considerable body of research into the links between experiences of parenting and the subsequent development of psychiatric morbidity, the nature and importance of such links in a student population has not been examined. The aims of this study were to establish the prevalence of substance misuse and psychiatric disorder in patients attending a student health service and to examine these in relation to perceived experiences of parenting. The study also aimed to assess the level of clinical detection of psychiatric disorders by general practitioners (GPs). Four hundred and thirty randomly selected attenders at a student health service completed a substance use and life style questionnaire, the General Health Questionnaire (GHQ) and the Parental Bonding Instrument. Psychiatric caseness, as defined by the GHQ, was compared with a retrospective review of comparable clinical case records. Fifty per cent of men and 32% of women exceeded sensible levels of alcohol consumption and 12% of men and 5% of women reported hazardous levels of alcohol intake. Cannabis was the most commonly used illicit substance, with 28% of men and 12% of women reporting regular use, while 64% of the subjects reported the use of any illicit drug. Sleep problems were common and the use of prescribed psychotropic drugs within the preceding year was reported by almost one-fifth of subjects. High levels of subjective stress, particularly financial, were associated with the use of illicit drugs (P < 0.01) and prescribed psychotropics (P < 0.0001). Sixty-five percent of women and 54% of men met the criteria for psychiatric caseness on the GHQ and this was associated with the use of illicit drugs (P < 0.01), prescribed psychotropics (P < 0.0001), sleep difficulties (P < 0.0001) and current stressors (P < 0.05). Defective parental bonding, particularly affectionless control (low care and overprotection), was associated with caseness on the GHQ (P < 0.0001), excessive alcohol consumption (P < 0.01) and sleep problems (P < 0.01). Psychological morbidity was recorded as present in 14% of consultations in the course of routine clinical practice. Psychological morbidity and substance misuse in students were significantly related to the styles of parenting experienced earlier in life. GPs working with students should be aware of the high prevalence of these problems in this population. Those responsible for higher education policy should take account of these findings and the fact that the presence of stressors such as financial worries was significantly associated with psychological distress, the prescription of psychotropic medication and the use of illicit drugs

Habitat association of plaice, sole and lemon sole in the English Channel

Flatfishes have been the subject of scientific research since the beginning of the 19th century but information on the specific habitat requirement of the adult life stages is largely anecdotal. Detailed knowledge of flatfish habitats however is a precondition for a more ecosystem orientated approach to fisheries management. Here the association between benthic habitat and the adult life stage of three flatfish species plaice (Pleuronectes platessa), sole (Solea solea) and lemon sole (Microstomus kitt) was investigated in the English Channel. Data from groundfish surveys spanning a period of 9 years was used to identify three distinct site groups: sites where a species occurred in consistently high abundances, sites of variable or low abundance and sites at which none were caught. Following the supposition of habitat selection theories such as the ideal free distribution theory these three sites groups should represent a gradient in habitat suitability from highly suitable to less suitable and unsuitable respectively. Habitat parameters and features for the three site groups and species were described and analysed. In particular sediment type and the importance of structuring epifauna for adult flatfish was investigated. Overall plaice and sole showed very similar trends for abiotic environmental parameters such as depth, temperature, salinity and tidal currents. Lemon sole was found over distinctly different habitats which may indicate a stronger niche partitioning of this species. Sediment associations differed between the three species with plaice predominantly occurring over sandy substrates with little mud and gravel content, while sole was found over a wider range of muddy to sandy substrates. Lemon sole was predominantly found over sand however containing a higher percentage of gravel than plaice. Structuring emergent epifauna was related positively to plaice and lemon sole abundances. These structures might be important as they tend to harbour larger numbers of epibenthic species upon which adult plaice and lemon sole prey. No such trend was found for the tactile feeding sole which mainly forages on infaunal polychaetes and molluscs