Use of biological reference points for the conservation of atlantic salmon (Salmo salar L.)in the River Lune, North West England.

This paper deals with the development and use of biological reference points for salmon conservation on the River Lune, England. The Lune supports recreational and net fisheries with annual catches in the region of 1,000 and 1356 salmon respectively. Using models transported from other river systems, biological reference points exclusive to the Lune were developed; specifically the number of eggs deposited and carrying capacity estimates for age 0+ and 1+ parr. The conservation limit was estimated at 11.9 million eggs and between 1989 and 1998 was exceeded in two years. Comparison of juvenile salmon densities in 1991 and 1997 with estimates of carrying capacity indicated that 0+ and 1+ parr densities were at around 60 % of carrying capacity and may relate to the number of eggs deposited in 1990 and 1996 being approximately 70% of the target value. The paper discusses the management actions taken in order to ensure that the management target of the conservation limit being met four years out of five is delivered. It also discusses the balance between conservation and exploitation and the socio-economic decisions made in order to ensure parity of impacts on the rod and net fisheries. The regulations have been enforced since 1999 and the paper concludes with an assessment of the actions taken to deliver the management targets, over the last five years.

Report of the Study Group on “Ecosystem-Based Management Science and its application to the North Pacific”

EXECUTIVE SUMMARY INTRODUCTION OVERVIEW OF INTERNATIONAL EBM HISTORY References CANADA Overview Activities to date Integrated Management implementation in Canada Objectives, indicators and reference points Assessment approaches Research directions for the future Management directions for the future References JAPAN Overview Conservation and sustainable use of marine living resources Harvest control by TAC system Stock Recovery Plan and effort regulation system Stock enhancement by hatchery-produced juvenile release Conservation and sustainable develop-ment on coastal waters The implementation of ecosystem-based management PEOPLE’S REPUBLIC OF CHINA Overview Current actions Output control Input control Summer fishing ban Enhance ecosystem health REPUBLIC OF KOREA Initiatives and actions of ecosystem-based management in Korea Current ecosystem-based management initiatives in Korea Precautionary TAC-based fishery management Closed fishing season/areas Fish size- and sex-controls Fishing gear design restrictions Marine protected areas (MPA) RUSSIA Existing and anticipated ecosystem-based management initiatives Issues related to the implementation of ecosystem-based management UNITED STATES OF AMERICA Definitions and approaches to ecosystem-based fishery management in the United States Present U.S. legislative mandates relating to ecosystem-based fishery management Target species Bycatch species Threatened or endangered species Habitats Food webs Ecosystems Integration of legislative mandates into an ecosystem approach Scientific issues in implementing ecosystem-based approaches References DISCUSSION AND RECOMMENDATIONS APPENDICES Appendix 10.1 Study group membership and participants Appendix 10.2 Terminology definitions Appendix 10.3 Present state of implementing ecosystem-based fishery management in Alaska: Alaska groundfish fisheries Appendix 10.4 Present state of implementing ecosystem-based fishery management off the West Coast of the United States: Pacific Coast groundfish fisheries Appendix 10.5 Descriptions of multi-species and ecosystem models developed or under development in the U.S. North Pacific region that might be used to predict effects of fishing on ecosystems Appendix 10.6 A potential standard reporting format (developed by Australia, and currently being used by the U.S.A in their contribution to this report) (83 page document)

Persistence and Non-target Impact of Imazapyr Associated with Smooth Cordgrass Control in an Estuary

The herbicide (±-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)- 5-oxo-1 H -imidazol-2-yl]-3-pyridinecarboxylic acid (imazapyr) has shown potential to control smooth cordgrass (Spartina alterniflora Loisel), a noxious weed in many estuaries throughout the world. Research was conducted under tidal estuary conditions in Willapa Bay, Washington, to determine imazapyr’s persistence and aquatic risk and impact to non-target estuary species. Persistence of imazapyr in water and sediment followed an exponential decay.(PDF has 6 pages.)

Non-target Impacts to Eelgrass from Treatments to Control Spartina in Willapa Bay, Washington

Four methods to control the smooth cordgrass Spartina (Spartina alterniflora) and the footwear worn by treatment personnelat several sites in Willapa Bay, Washington were evaluatedto determine the non-target impacts to eelgrass (Zostera japonica). Clone-sized infestations of Spartina were treated bymowing or a single hand-spray application of Rodeo® formulatedat 480 g L-1acid equivalence (ae) of the isopropylaminesalt of glyphosate (Monsanto Agricultural Co., St. Louis, MO;currently Dow AgroSciences, Indianapolis, IN) with the nonionic surfactant LI 700® (2% v/v) or a combination of mowing and hand spraying. An aerial application of Rodeo® with X-77 Spreader® (0.13% v/v) to a 2-ha meadow was also investigated. Monitoring consisted of measuring eelgrass shoot densities and percent cover pre-treatment and 1-yr post-treatment. Impacts to eelgrass adjacent to treated clones were determined 1 m from the clones and compared to a control 5-m away. Impacts from footwear were assessed at 5 equidistant intervals along a 10-m transect on mudflat and an untreated control transect at each of the three clone treatment sites. Impacts from the aerial application were determined by comparing shoot densities and percent cover 1, 3 and 10 m from the edge of the treated Spartina meadow to that at comparable distances from an untreated meadow. Methods utilized to control Spartina clones did not impact surrounding eelgrass at two of three sites. Decreases in shoot densities observed at the third site were consistent across treatments. Most impacts to eelgrass from the footwear worn by treatment personnel were negligible and those that were significant were limited to soft mud substrate. The aerial application of the herbicide was associated with reductions in eelgrass (shoot density and percent cover) at two of the three sampling distances, but reductions on the control plot were greater. We conclude that the unchecked spread of Spartina is a far greater threat to the survival and health of eelgrass than that from any of the control measures we studied. The basis for evaluating control measures for Spartina should be efficacy and logistical constraints and not impacts to eelgrass. PDF is 7 pages.

Stock assessment of protogynous fish: evaluating measures of spawning biomass used to estimate biological reference points

In stock assessments, recruitment is typically modeled as a function of females only. For protogynous stocks, however, disproportionate fishing on males increases the possibility of reduced fertilization rates. To incorporate the importance of males in protogynous stocks, assessment models have been used to predict recruitment not just from female spawning biomass (Sf), but also from that of males (Sm) or both sexes (Sb). We conducted a simulation study to evaluate the ability of these three measures to estimate biological reference points used in fishery management. Of the three, Sf provides best estimates if the potential for decreased fertilization is weak, whereas Sm is best only if the potential is very strong. In general, Sb estimates the true reference points most closely, which indicates that if the potential for decreased fertilization is moderate or unknown, Sb should be used in assessments of protogynous stocks. Moreover, for a broad range of scenarios, relative errors from Sf and Sb occur in opposite directions, indicating that estimates from these measures could be used to bound uncertainty.

Blue Crab target setting: final report

We have developed a hierarchy of target levels, designated to address sustainability, efficiency, and recovery scenarios. Targets were derived from: 1) reported catches and effort in the commercial fishery, 2) statistics from fishery-independent surveys, and 3) knowledge of the biology of blue crab. Targets that are recommended include population sizes, catches, and effort levels, as well as reference fishing mortality rates. They are intended to be conservative and risk-averse. (PDF contains 182 pages)

Die Fischereiressourcen im Hinblick auf deutsche Interessen

The North-European fish stocks are assessed annually by ICES working groups. The results are evaluated twice annually in two meetings of the Advisory Committee for Fisheries Management (ACFM) at ICES. Based on the working group assessments, ACFM formulates an advice for the fisheries management and suggests a total allowable catch (TAC) which is based strictly on biological grounds. The summaries of the state of some selected stocks which are given here, are derived from the ACFM advice, formulated during the most recent October 1999 meeting. For many of the fish stocks the precautionary approach has been implemented now, and for most of them the target reference points have been defined. As a result, most of the stocks are outside safe biological limits or are harvested in disaccordance with the precautionary approach. Only 10 stocks of those evaluated during this autumn meeting were found to be within safe biological limits.

Lage und Entwicklung der Fischereiressources in Hinblick auf deutsche Fischereiinteressen

The northern European fish stocks are assessed annually by ICES working groups. The results are evaluated biannually in two meetings of the Advisory Committee for Fisheries Management (ACFM) at ICES. Based on the working group assessments, ACFM formulates an advice for fisheries management and suggests a total allowable catch (TAC) which is based strictly on biological grounds. The summaries of the state of some selected stocks which are given here, are derived from the ACFM advice, formulated during the most recent May 1998 meeting. For many of the fish stocks the precautionary approach is still in the process of implementation, and only for some of them the management and target reference points have been fully defined.

Lage und Entwicklung der Fischereiressourcen im Hinblick auf deutsche Fischereiinteressen: Neuste Bestandsabschätzung des ACFM

The North European fish stocks are assessed annually by ICES working groups. The results are evaluated biannually in two meetings of the Advisory Committee for Fisheries Management (ACFM) at ICES. Based on the working group assessments, ACFM formulates an advice for fisheries management and suggests a total allowable catch (TAC) which is based strictly on biological grounds. The summaries of the state of some selected stocks which are given here, are derived from the ACFM advice, formulated during the most recent Oktober 1998 meeting. For many of the fish stocks the precautionary approach is still in the process of implementation, however for most of them the management and target reference points have been fully defined by now.

Aquatic insects as target organisms for the study of effects of projected climate change in the British Isles

One of the objectives of the Terrestrial Initiative in Global Environmental Research is to assess the sensitivity of British plant and animal species to climate change. The first phase of the program involved the identification of criteria for selecting species suitable for the study of effects of projected climate change in the British Isles. Apart from shallow ponds, annual temperature ranges of 0 to 25 C in temperate freshwater habitats are narrower than those in most temperate terrestrial habitats. Although freshwater organisms have to exist within a narrower range than their terrestrial equivalents, few species can survive throughout their life cycle over the whole temperature range. Field studies on the effects of natural and artificial thermal discharges into streams and rivers have shown that increases in water temperature affect aquatic insects at both the species and community level. Although field data provide valuable information, a more productive approach is to determine experimentally the requirements of different species. Although there are just over 1850 species of aquatic insects in the British Isles, detailed quantitative information on the relationship between temperature and development of eggs, larvae and pupa is available for relatively few species. One exception is the egg stage of stoneflies (Plecoptera). The range for egg hatching in stoneflies clearly show that some species could be threatened while others could benefit from a defined increase in water temperature as a result of climate change. A critical review of the available data on this group would produce a set of equations that could be used to predict the ecological effects of climate change on this group of indicator species.

Design of a Recreational Fishing Survey and Mark-Recapture Study for the Blue Crab, Callinectes sapidus, in Chesapeake Bay

The development of bay wide estimates of recreational harvest has been identified as a high priority by the Chesapeake Bay Scientific Advisory Committee (CBSAC) and by the Chesapeake Bay Program as reflected in the Chesapeake Bay Blue Crab Fishery Management Plan (Chesapeake Bay Program 1996). In addition, the BiState Blue Crab Commission (BBCAC), formed in 1996 by mandate from the legislatures of Maryland and Virginia to advise on crab management, has also recognized the importance of estimating the levels and trends in catches in the recreational fishery. Recently, the BBCAC has adopted limit and target biological reference points. These analyses have been predicated on assumptions regarding the relative magnitude of the recreational and commercial catch. The reference points depend on determination of the total number of crabs removed from the population. In essence, the number removed by the various fishery sectors, represents a minimum estimate of the population size. If a major fishery sector is not represented, the total population will be accordingly underestimated. If the relative contribution of the unrepresented sector is constant over time and harvests the same components of the population as the other sectors, it may be argued that the population estimate derived from the other sectors is biased but still adequately represents trends in population size over time. If either of the two constraints mentioned above is not met, the validity of relative trends over time is suspect. With the recent increases in the human population in the Chesapeake Bay watershed, there is reason to be concerned that the recreational catch may not have been a constant proportion of the total harvest over time. It is important to assess the catch characteristics and the magnitude of the recreational fishery to evaluate this potential bias. (PDF contains 70 pages)

Aquatic insects as target organisms for the study of effects of projected climate change in the British Isles

The chief objectives of this brief review are to collate and synthesise quantitative information on the temperature requirements of aquatic insects, and to identify species, and groups of species, that could be useful indicators of climate change and predictors of the ecological effects of change. It arose from the first phase of the Terrestrial Initiative in Global Environmental Research (TIGER), a five-year, NERC Community Programme on the role of the terrestrial biosphere in the science of global change. This phase involved the identification of criteria for selecting species suitable for the study of effects of projected climate change in the British Isles. Field and laboratory studies are reviewed, and criteria for selection of species for future research are suggested. The literature survey shows that no species of aquatic insect can be found to meet all three criteria, but information on the British stoneflies and their eggs already satisfies two of them.

Analysis of sex-specific spawning biomass per recruit of the sailfish (Istiophorus platypterus) in the waters off eastern Taiwan

Analyses of sex-specific yield per recruit and spawning stock biomass per recruit were conducted to evaluate the current status of the sailfish (Istiophorus platypterus) fishery in the waters off eastern Taiwan. Natural mortality rates estimated from Pauly’s empirical equation were 0.26/yr for females and 0.27/yr for males. The current fishing mortality rates were estimated as 0.24/yr and 0.43/yr for females and males, respectively, which are much lower than the estimated F0 .1 (0.62/yr and 0.79/yr for females and males, respectively) and FSSB40 (0.46/yr for females) which are commonly used as target reference points in fisheries management. The effects of the fishing mortality, natural mortality, and age at first capture on the estimates of biological reference points were evaluated by using the Monte Carlo simulation. The results indicate that failure to consider the uncertainty in parameters such as natural mortality or age at first capture may lead to the improper estimation of biological reference points. This study indicates the possibility of current fishing mortality exceeding the target biological reference points may be negligible for sailfish in the waters off eastern Taiwan. However, in view of the recent rapid increase in fishing effort, it is evident that the stock status and development of the fishery need to be closely monitore

Multiple stable reference points in oyster populations: biological relationships for the eastern oyster (Crassostrea virginica) in Delaware Bay

Abstract—In the first of two companion papers, a 54-yr time series for the oyster population in the New Jersey waters of Delaware Bay was analyzed to develop biological relationships necessary to evaluate maximum sustainable yield (MSY) reference points and to consider how multiple stable points affect reference point-based management. The time series encompassed two regime shifts, one circa 1970 that ushered in a 15-yr period of high abundance, and a second in 1985 that ushered in a 20-yr period of low abundance. The intervening and succeeding periods have the attributes of alternate stable states. The biological relationships between abundance, recruitment, and mortality were unusual in four ways. First, the broodstock–recruitment relationship at low abundance may have been driven more by the provision of settlement sites for larvae by the adults than by fecundity. Second, the natural mortality rate was temporally unstable and bore a nonlinear relationship to abundance. Third, combined high abundance and low mortality, though likely requiring favorable environmental conditions, seemed also to be a self-reinforcing phenomenon. As a consequence, the abundance –mortality relationship exhibited both compensatory and depensatory components. Fourth, the geographic distribution of the stock was intertwined with abundance and mortality, such that interrelationships were functions both of spatial organization and inherent populatio

Multiple stable reference points in oyster populations: implications for reference point-based management

In the second of two companion articles, a 54-year time series for the oyster population in the New Jersey waters of Delaware Bay is analyzed to examine how the presence of multiple stable states affects reference-point–based management. Multiple stable states are described by four types of reference points. Type I is the carrying capacity for the stable state: each has associated with it a type-II reference point wherein surplus production reaches a local maximum. Type-II reference points are separated by an intermediate surplus production low (type III). Two stable states establish a type-IV reference point, a point-of-no-return that impedes recovery to the higher stable state. The type-II to type-III differential in surplus production is a measure of the difficulty of rebuilding the population and the sensitivity of the population to collapse at high abundance. Surplus production projections show that the abundances defining the four types of reference points are relatively stable over a wide range of uncertainties in recruitment and mortality rates. The surplus production values associated with type-II and type-III reference points are much more uncertain. Thus, biomass goals are more easily established than fishing mortality rates for oyster population