Dataset Information

Ecological indicators display reduced variation in North American catch share fisheries.

ABSTRACT: A growing push to implement catch share fishery programs is based partly on the recognition that they may provide stronger incentives for ecological stewardship than conventional fisheries management. Using data on population status, quota compliance, discard rates, use of habitat-damaging gear, and landings for 15 catch share programs in North America, I tested the hypothesis that catch share systems lead to improved ecological stewardship and status of exploited populations. Impacts of catch share programs were measured through comparisons of fisheries with catch shares to fisheries without catch shares or by comparing fisheries before and after catch shares were implemented. The average levels of most indicators were unaffected by catch share implementation: only discard rate, which declined significantly in catch share fisheries, showed a significant response. However, catch share fisheries were distinguished by markedly reduced interannual variability in all indicators, being statistically significant for exploitation rate, landings, discard rate, and the ratio of catch to catch quotas. These impacts of catch shares were common between nations and ocean basins and were independent of the number of years that catch share programs had been in place. These findings suggest that for the indicators examined, the primary effect of catch shares was greater consistency over time. This enhanced consistency could be beneficial to fishery systems and might also be an indication of more effective management.

SUBMITTER: Essington TE

PROVIDER: S-EPMC2818897 | biostudies-other | 2010 Jan

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Ecological indicators display reduced variation in North American catch share fisheries.

Essington Timothy E TE

Proceedings of the National Academy of Sciences of the United States of America 20091222 2

A growing push to implement catch share fishery programs is based partly on the recognition that they may provide stronger incentives for ecological stewardship than conventional fisheries management. Using data on population status, quota compliance, discard rates, use of habitat-damaging gear, and landings for 15 catch share programs in North America, I tested the hypothesis that catch share systems lead to improved ecological stewardship and status of exploited populations. Impacts of catch s ...[more]

PMID: 20080747

Similar Datasets

Project description:There is considerable variability in the status of fish populations around the world and a poor understanding of how specific management characteristics affect populations. Overfishing is a major problem in many fisheries, but in some regions the recent tendency has been to exploit stocks at levels below their maximum sustainable yield. In Western North American groundfish fisheries, the status of individual stocks and management systems among regions are highly variable. In this paper, we show the current status of groundfish stocks from Alaska, British Columbia, and the U.S. West Coast, and quantify the influence on stock status of six management tactics often hypothesized to affect groundfish. These tactics are: the use of harvest control rules with estimated biological reference points; seasonal closures; marine reserves; bycatch constraints; individual quotas (i.e., 'catch shares'); and gear type. Despite the high commercial value of many groundfish and consequent incentives for maintaining stocks at their most productive levels, most stocks were managed extremely conservatively, with current exploitation rates at only 40% of management targets and biomass 33% above target biomass on average. Catches rarely exceeded TACs but on occasion were far below TACs (mean catch:TAC ratio of 57%); approximately $150 million of potential landed value was foregone annually by underutilizing TACs. The use of individual quotas, marine reserves, and harvest control rules with estimated limit reference points had little overall effect on stock status. More valuable fisheries were maintained closer to management targets and were less variable over time than stocks with lower catches or ex-vessel prices. Together these results suggest there is no single effective management measure for meeting conservation objectives; if scientifically established quotas are set and enforced, a variety of means can be used to ensure that exploitation rates and biomass levels are near to or more conservative than management targets.

Project description:BackgroundPostnatally, small-for-gestational-age (SGA; birthweight <10th centile) infants who are growth restricted due to uteroplacental insufficiency (UPI) demonstrate 'catch-up growth' to meet their genetically-predetermined size. Infants who demonstrate slowing growth during pregnancy are those that cross estimated fetal weight centiles at serial ultrasound examinations. These infants that slow in growth but are born appropriate-for-gestational-age (AGA; ≥10th centile), exhibit antenatal, intrapartum and postnatal indicators of UPI. Here, we examine if and when these infants (labelled as AGA-FGR) also demonstrate catch-up growth like SGA infants, when compared with AGA infants with normal antenatal growth velocity (AGA-NG).MethodsWe followed-up the infants of women who had previously undergone ultrasound assessment of fetal size at 28- and 36-weeks' gestation, enabling calculation of antenatal growth velocity. To assess postnatal growth, we asked parents to send their infant's growth measurements, up to two years post-birth, which are routinely collected through the state-wide Maternal-Child Health service. Infants with medical conditions affecting postnatal growth were excluded from the analysis. From the measurements obtained we calculated age-adjusted z-scores for postnatal weight, length and body mass index (BMI; weight(kg)/height(m2)) at birth and 4, 8, 12, 18 and 24 months. We used linear spline regression modelling to predict mean weight, length and BMI z-scores at intervals post birth. Predicted mean age-adjusted z-scores were then compared between three groups; SGA, AGA with low antenatal growth (AGA-FGR; loss of >20 customised estimated fetal weight centiles), and AGA-NG to determine if catch-up growth occurred. In addition, we compared the rates of catch-up growth (defined as an increase in weight age-adjusted z-score of ≥0.67 over 1 year) between the groups with Fisher's exact tests.ResultsOf 158 (46%) infant growth records received, 146 were AGA, with low antenatal growth velocity occurring in 34/146 (23.2%). Rates of gestational diabetes and SGA birthweight were higher in those lost to follow-up. Compared to AGA-NG infants, AGA-FGR infants had significantly lower predicted mean weight (p<0.001), length (p = 0.04) and BMI (p = 0.001) z-scores at birth. These significant differences were no longer evident at 4 months, suggesting that catch-up growth had occurred. As expected, the catch-up growth that occurred among the AGA-FGR was not as great in magnitude as that demonstrated by the SGA. When assessed categorically, there was no significant difference between the rate of catch-up growth among the AGA-FGR and the SGA. Catch-up growth was significantly more frequent among both the AGA-FGR and the SGA groups compared to the AGA-NG.ConclusionsAGA infants that have exhibited reduced antenatal fetal growth velocity also exhibit significant catch-up growth in the first 12 months of life. This finding represents further evidence that AGA fetuses that slow in growth during pregnancy do so due to UPI.

Dataset Information

Ecological indicators display reduced variation in North American catch share fisheries.

Publications

Ecological indicators display reduced variation in North American catch share fisheries.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets