Bridget S. Green

Maternal effects in fish populations.

Recently, the importance of the female to population dynamics-especially her non-genetic contribution to offspring fitness or maternal effect-has received much attention in studies of a diverse collection of animal and plant taxa. Of particular interest to fisheries scientists and managers is the role of the demographic structure of the adult component of fish populations in the formation of future year classes. Traditionally, fisheries managers tended to assess whole populations without regard to variation between the individuals within the population. In doing so, they overlooked the variation in spawning production between individual females as a source of variation to recruitment magnitude and fluctuation. Indeed, intensive and/or selective harvesting of larger and older females, those that may produce more-and higher quality-offspring, has been implicated in the collapse of a number of important fish stocks. In a fisheries resource management context, whether capture fisheries or aquaculture, female demographics and inter-female differences warrant serious consideration in developing harvesting and breeding strategies, and in understanding general population dynamics. Here I review the range of female traits and environmental conditions females encounter which may influence the number or quality of their offspring via a maternal effect.

Tropical fish otoliths : information for assessment, management and ecology

Techniques and theory for processing otoliths from tropical marine fish have developed only recently due to an historic misconception that these organisms could not be aged. Otoliths are the most commonly used structures from which daily, seasonal or annual records of a fish’s environmental history are inferred, and are also used as indicators of migration patterns, home range, spatial distribution, stock structure and life history events. A large proportion of projects undertaken on tropical marine organisms involve removal and processing of calcified structures such as otoliths, statoliths or vertebrae to retrieve biological, biochemical or genetic information. Current techniques and principles have evolved rapidly and are under constant modification and these differ among laboratories, and more particularly among species and within life history stages. Tropical fish otoliths: Information for assessment, management and ecology is a comprehensive description of the current status of knowledge about otoliths in the tropics. This book has contributions from leading experts in the field, encompasing a tropical perspective on daily and annual ageing in fish and invertebrates, microchemistry, interpreting otolith microstructure and using it to back-calculate life history events, and includes a treatise on the significance of validating periodicity in otoliths.

Marine foods sourced from farther as their use of global ocean primary production increases

The growing human population must be fed, but historic land-based systems struggle to meet expanding demand. Marine production supports some of the worlds poorest people but increasingly provides for the needs of the affluent, either directly by fishing or via fodder-based feeds for marine and terrestrial farming. Here we show the expanding footprint of humans to utilize global ocean productivity to feed themselves. Our results illustrate how incrementally each year, marine foods are sourced farther from where they are consumed and moreover, require an increasing proportion of the oceans primary productivity that underpins all marine life. Though mariculture supports increased consumption of seafood, it continues to require feeds based on fully exploited wild stocks. Here we examine the oceans ability to meet our future demands to 2100 and find that even with mariculture supplementing near-static wild catches our growing needs are unlikely to be met without significant changes.

Ontogeny of the digestive and feeding systems in the anemonefish Amphiprion melanopus

Ontogenetic growth and development in the anemonefish Amphiprion melanopus (Pomacentridae) is very rapid when compared to other tropical and temperate fish species. A. melanopus hatched with a highly differentiated digestive tract and the ability to capture and ingest prey items. Their alimentary tract changes rapidly throughout the larval period. Concurrent with yolksac absorption at three days after hatching was the development of the stomach followed by calcification of the jaw structures. This period of acute structural change may be a critical period in their development. Metamorphosis coincided with settlement at 8 days after hatching and was marked by calcification of fins and acquirement of adult coloration. The rapid development found in this species may be a specialisation to enhance the return of larvae to a patchy and highly specific settlement habitat.

The Good, the Bad and the Recovery in an Assisted Migration

Background Assisted migration or translocation of species to ameliorate effects of habitat loss or changing environment is currently under scrutiny as a conservation tool. A large scale experiment of assisted migration over hundreds of kilometres was tested on a morph from a commercial fishery of southern rock lobster Jasus edwardsii, to enhance depleted populations, improve the yield and sustainability of the fishery, and test resilience to a changing climate. Methodology and Principal Findings Approximately 10,000 lower-valued, pale-coloured lobsters were moved from deep water to inshore sites (2 in Tasmania [TAS] and 2 in South Australia [SA]) where the high-value, red morph occurs. In TAS this was a northwards movement of 1° latitude. Growth was measured only in TAS lobsters, and reproductive status was recorded in lobsters from all locations. Pale females (TAS) grew 4 times faster than resident pale lobsters from the original site and twice as fast as red lobsters at their new location. Approximately 30% of translocated pale lobsters deferred reproduction for one year after release (SA and TAS), and grew around 1 mm yr−1 less compared to translocated pale lobsters that did not defer reproduction. In spite of this stress response to translocation, females that deferred reproduction still grew 2–6 mm yr−1 more than lobsters at the source site. Lobsters have isometric growth whereby volume increases as a cube of length. Consequently despite the one-year hiatus in reproduction, increased growth increases fecundity of translocated lobsters, as the increase in size provided a larger volume for producing and incubating eggs in future years. Conclusions and Significance Assisted migration improved egg production and growth, despite a temporary stress response, and offers a tool to improve the production, sustainability and resilience of the fishery.

Environmental effects on fished lobsters and crabs

AbstractThe fisheries for crabs and lobsters (Reptantia, Decapoda) are shaped by environmental variation through the distribution ecology, productivity or even their market traits such as colour and size. Many crabs and lobsters have a wide latitudinal distribution and therefore are exposed to significant abiotic gradients throughout their geographic range. Environmental factors affect reptantians throughout their complex life cycle, including embryo development, timing and length of the spawning period, the duration and quality of the larval stages, the level and spatial distribution of the settlement, growth rates and size of the juveniles, size at maturity, and catchability. The most consistent environmental response is of growth and reproduction to temperature. Growth rates increase with increasing temperatures in a parabolic function, tapering and then declining as the boundaries of thermal tolerance are reached. With increasing temperature the intermoult duration decreases. Once the upper thermal boundary is reached, increases in temperature result in longer intermoult duration and smaller growth increments so that growth is reduced. Declines in temperature generally suppress moulting, and consequently reptantians rarely moult in winter. Increasing temperature decreases the time for egg incubation, larval development and the maturational age. Catchability increases with water temperature and also varies, although less predictably, with moon phase and wind strength. Catchability decreases with an increase in population density. Larval settlement of many reptantian species depends on current strength, increasing with the strength of certain local currents. Reptantians can tolerate a wide-variety of conditions and have flexible life-histories to respond to conditions throughout their broad geographic ranges. Information on environmental effects on reptantians not only assists in understanding probable effects of ocean warming and acidification, but also seasonal and interannual changes in fisheries production.

Price integration in the Australian rock lobster industry: implications for management and climate change adaptation

Rock lobster fisheries are Australias most valuable wild fisheries in terms of both value of production and value of exports. Different states harvest and export different lobster species, with most of the landings being sent to the Hong Kong market. A perception in the Australian lobster industry is that the different species are independent on the export market, such that a change in landings of one species has no impact on the price of the others. This study investigates the market integration of Australian exports to Hong Kong for the four species and different exporting states. Our results indicate all four species and producers/export states are perceived to be substitutes for one another, so that, in the long run, prices paid to operators in the industry will move together. The integrated nature of the Hong Kong export market for Australian lobster suggests that the potential impacts of alternative fisheries management and development strategies at state and species levels cannot be considered in isolation, at least from an economic perspective. In addition, impacts of external shocks affecting production in one state (e.g. climate change) can be expected to affect all Australian lobster fisheries.

A quantitative metric to identify critical elements within seafood supply networks

A theoretical basis is required for comparing key features and critical elements in wild fisheries and aquaculture supply chains under a changing climate. Here we develop a new quantitative metric that is analogous to indices used to analyse food-webs and identify key species. The Supply Chain Index (SCI) identifies critical elements as those elements with large throughput rates, as well as greater connectivity. The sum of the scores for a supply chain provides a single metric that roughly captures both the resilience and connectedness of a supply chain. Standardised scores can facilitate cross-comparisons both under current conditions as well as under a changing climate. Identification of key elements along the supply chain may assist in informing adaptation strategies to reduce anticipated future risks posed by climate change. The SCI also provides information on the relative stability of different supply chains based on whether there is a fairly even spread in the individual scores of the top few key elements, compared with a more critical dependence on a few key individual supply chain elements. We use as a case study the Australian southern rock lobster Jasus edwardsii fishery, which is challenged by a number of climate change drivers such as impacts on recruitment and growth due to changes in large-scale and local oceanographic features. The SCI identifies airports, processors and Chinese consumers as the key elements in the lobster supply chain that merit attention to enhance stability and potentially enable growth. We also apply the index to an additional four real-world Australian commercial fishery and two aquaculture industry supply chains to highlight the utility of a systematic method for describing supply chains. Overall, our simple methodological approach to empirically-based supply chain research provides an objective method for comparing the resilience of supply chains and highlighting components that may be critical.

Super Trawler Scuppered in Australian Fisheries Management Reform

ABSTRACT In response to an intense social media campaign led by international conservation groups, Green politicians, and recreational fishers, the Australian government imposed a moratorium on the operations of a large factory trawler. This moratorium overrode the governments own independent fisheries management process by making amendments to its key environmental legislation just days prior to the commencement of fishing by this vessel. Concurrently, the government announced a comprehensive review of Australias fisheries management legislation. Whereas science is usually deployed in support of conservation in natural resource conflicts, in this case science-based fisheries management advice took a back seat to vociferous protest by interest groups, perpetuated by the media (in particular social media), ultimately culminating in a contentious political decision.

Facing the wave of change: stakeholder perspectives on climate adaptation for Australian seafood supply chains

Climate change is one of the most important issues confronting the sustainable supply of seafood, with projections suggesting major effects on wild and farmed fisheries worldwide. While climate change has been a consideration for Australian fisheries and aquaculture management, emphasis in both research and adaptation effort has been at the production end of supply chains—impacts further along the chain have been overlooked to date. A holistic biophysical and socio-economic system view of seafood industries, as represented by end-to-end supply chains, may lead to an additional set of options in the face of climate change, thus maximizing opportunities for improved fishery profitability, while also reducing the potential for maladaptation. In this paper, we explore Australian seafood industry stakeholder perspectives on potential options for adaptation along seafood supply chains based on future potential scenarios. Stakeholders, representing wild capture and aquaculture industries, provided a range of actions targeting different stages of the supply chain. Overall, proposed strategies were predominantly related to the production end of the supply chain, suggesting that greater attention in developing adaptation options is needed at post-production stages. However, there are chain-wide adaptation strategies that can present win–win scenarios, where commercial objectives beyond adaptation can also be addressed alongside direct or indirect impacts of climate. Likewise, certain adaptation strategies in place at one stage of the chain may have varying implications on other stages of the chain. These findings represent an important step in understanding the role of supply chains in effective adaptation of fisheries and aquaculture industries to climate change.