Effects of commercial fishing regulations on stranding rates of bottlenose dolphin (Tursiops truncatus).

Fisheries management actions taken to protect one species can have unintended, and sometimes positive, consequences on other species. For example, regulatory measures to reduce fishing effort in the winter gillnet fishery for spiny dogfish (Squalus acanthias) off North Carolina (NC) also led to decreases in the number of bycaught bottlenose dolphins (Tursiops truncatus). This study found that a marked decrease in fishing effort for spiny dogfish in NC also corresponded with a marked decrease in winter stranding rates of bottlenose dolphins with entanglement lesions (P= 0.002). Furthermore, from 1997 through 2002, there was a significant positive correlation (r2 = 0.79; P= 0.0003) between seasonal bycatch estimates of bottlenose dolphins in gill nets and rates of stranded dolphins with entanglement lesions. With this information, stranding thresholds were developed that would enable the detection of those increases in bycatch in near real-time. This approach is valuable because updated bycatch estimates from observer data usually have a time-lag of two or more years. Threshold values could be used to detect increases in stranding rates, triggering managers immediately to direct observer effort to areas of potentially high bycatch or to institute mitigation measures. Thus, observer coverage and stranding investigations can be used in concert for more effective fishery management.

Climate change adaptation and planning: An example from Kailua Beach, Oahu, Hawaii

The University of Hawaii Sea Grant College Program (UHSG) in partnership with the Hawaii Department of Land and Natural Resources (DLNR), Office of Conservation and Coastal Lands (OCCL) is developing a beach and dune management plan for Kailua Beach on the eastern shoreline of Oahu. The objective of the plan is to develop a comprehensive beach management and land use development plan for Kailua Beach that reflects the state of scientific understanding of beach processes in Kailua Bay and abutting shoreline areas and is intended to provide long-term recommendations to adapting to climate change including potential coastal hazards such as sea level rise. The development of the plan has lead to wider recognition of the significance of projected sea level rise to the region and provides the rational behind some of the land use conservation strategies. The plan takes on a critical light given global predictions for continued, possibly accelerated, sea-level rise and the ongoing focus of intense development along the Hawaiian shoreline. Hawaii’s coastal resource managers are faced with the daunting prospect of managing the effects of erosion while simultaneously monitoring and regulating high-risk coastal development that often impacts the shoreline. The beach and dune preservation plan is the first step in a more comprehensive effort prepare for and adapt to sea level rise and ensure the preservation of the beach and dune ecosystem for the benefit of present and future generations. The Kailua Beach and Dune Management plan is intended to be the first in a series of regional plans in Hawaii to address climate change adaptation through land use planning. (PDF contains 3 pages)

The dynamics of the fecundity of fishes, for example the roach, Rutilus rutilus (L.). [conclusions and figure/table captions only] [Translation from: Voprosy Ikhtiologii 3(1) 67-83, 1963]

The dynamics of the fecundity of roach, with emphasis on Rutilus rutilus (L.), were studied in waters in the European parts of the USSR. This translation provides conclusions, and figures and table captions only.

Aspects of the washout of salmonid eggs. 1. Observations on the physical characteristics of real and artificial eggs, their rate of fall in a water column and their pattern of settlement in an experimental channel

When salmonid redds are disrupted by spates, the displaced eggs will drift downstream. The mean distance of travel, the types of locations in which the eggs resettle and the depth of reburial of displaced eggs are not known. Investigation of these topics under field conditions presents considerable practical problems, though the use of artificial eggs might help to overcome some of them. Attempts to assess the similarities and/or differences in performance between real and artificial eggs are essential before artificial eggs can validly be used to simulate real eggs. The present report first compares the two types of egg in terms of their measurable physical characteristics (e.g. dimensions and density). The rate at which eggs fall in still water will relate to the rate at which they are likely to resettle in flowing water in the field. As the rate of fall will be influenced by a number of additional factors (e.g. shape and surface texture) which are not easily measured directly, the rates of fall of the two types of egg have been compared directly under controlled conditions. Finally, comparisons of the pattern of settlement of the two types of egg in flowing water in an experimental channel have been made. Although the work was primarily aimed at testing the value of artificial eggs as a simulation of real eggs, several side issues more directly concerned with the properties of real eggs and the likely distance of drift in natural streams have also been explored. This is the first of three reports made on this topic by the author in 1984.

Simple broodstock management to control indirect selection and inbreeding: Indian carp example

Following a survey of the important traits of Indian carp broodstock at some southern Indian hatcheries, it was found that the broodstock selection was size selective, exerting strong, negative selection of prematuration growth rate and positive selection on age at first maturation. This meant that the hatchery bred inadvertently slower growing and later maturing individuals. Details are given of approaches to avoid such negative selection and minimize inbreeding.

Reducing Prawn-trawl Bycatch in Australia: An Overview and an Example from Queensland

Prawn trawling occurs in most states of Australia in tropical, subtropical, and temperate waters. Bycatch occurs to some degree in all Australian trawl fisheries, and there is pressure to reduce the levels of trawl fishery bycatch. This paper gives a brief overview of the bycatch issues and technological solutions that have been evaluated or adopted in Australian prawn-trawl fi sheries. Turtle excluder devices (TED’s) and bycatch reduction devices (BRD’s) are the principal solutions to bycatch in Australian prawn-trawl fisheries. This paper focuses on a major prawn-trawl fishery of northeastern Australia, and the results of commercial use of TED’s and BRD’s in the Queensland east coast trawl fishery are presented. New industry designs are described, and the status of TED and BRD adoption and regulation is summarized. The implementation of technological solutions to reduce fishery bycatch is assumed generally to assist prawn-trawl fisheries within Australia in achieving legislative requirements for minimal environmental impact and ecological sustainable development.

Survey Assessment of Semi-pelagic Gadoids: The Example of Walleye Pollock, Theragra chalcogramma, in the Eastern Bering Sea

Assessment of walleye pollock, Theragra chalcogramma, in the eastern Bering Sea is complicated because the species is semi-pelagic in habit. Annual bottom trawl surveys provide estimates of demersal abundance on the eastern Bering Sea shelf. Every third year (starting in 1979), an extended area of the shelf and slope is surveyed and an echo integration-midwater trawl survey provides estimates of pollock abundance in midwater. Overall age-specific population and biomass estimates are obtained by summing the demersal and midwater results, assuming that the bottom trawl samples only pollock inhabiting the lower 3 m of the water column. Total population estimates have ranged from 134 x 109 fish in 1979 to 27 x 109 fish in 1988. The very high abundance observed in 1979 reflects the appearance of the unusually large 1978 year class. Changes in age-specific abundance estimates have documented the passage of strong (1978, 1982, and 1984) and weak year classes through the fishery. In general, older fish are more demersally oriented and younger fish are more abundant in midwater, but this trend was not always evident in the patterns of abundance of 1- and 2-year-old fish. As the average age of the population has increased, so has the relative proportion of pollock estimated by the demersal surveys. Consequently, it is unlikely that either technique can be used independently to monitor changes in abundance and age composition. Midwater assessment depends on pelagic trawl samples for size and age composition estimates, so both surveys are subject to biases resulting from gear performance and interactions between fish and gear. In this review, we discuss survey methodology and evaluate assumptions regarding catchability and availability as they relate to demersal, midwater, and overall assessment.