The lay system in commercial fisheries: Origin and implications

In most commercial fisheries, the crew is remunerated via some form of the lay system. Under the lay system, the crew is paid with a share of revenues or a share of revenues less costs. Naturally, the presence and the functioning of the lay system are well known and accepted as one of fishery's important institutions. Compared with share contracts in agriculture, however, the lay in fisheries has garnered relatively little research. This article has two goals. First, we provide an explanation for the existence of the lay system as an incentive mechanism to alleviate a potential team agency problem. This explanation of the lay system explains anomalies, such as the presence of wages in some fisheries, that are odds with the theory of pure risk sharing. Second we show the implications of the lay system for econometric modeling of fisheries and for understanding firm behavior. In general we conclude that models that fail to account explicitly for the incentive properties of shares are likely to provide poor representations of fishing firm behavior. The thrust of the paper is that the formation and working of the lay system are a fundamental force in fisheries influencing firm behavior and research results in a way that has been largely ignored.     

Quantifying and comparing size selectivity among Alaskan sockeye salmon fisheries

Quantifying long-term size-selective harvest patterns is necessary for understanding the potential evolutionary effects on exploited species. The comparison of fishery selection patterns on the same species subject to different gear types, in different areas, and over multi-decadal periods can reveal the factors influencing selection. In this study we quantified and compared size-selective harvest by nine Alaskan sockeye salmon (Oncorhynchus nerka) fisheries to understand overall patterns. We calculated length-specific linear selection differentials (the difference in average length of fish before vs. after fishing), which are produced by different combinations of exploitation rates and length-selectivity values, and nonlinear standardized differentials, describing disruptive selection, across all years for each fishery. Selection differentials varied among years, but larger fish were caught in 73% of years for males and 84% of years for females, leaving smaller fish to spawn. Disruptive selection was observed on female and male fish in 84% and 92% of years, respectively. Linear selection was stronger on females than males in 77% of years examined, and disruptive selection was stronger on males in 71% of years. Selection pressure was influenced by a combination of factors under and beyond management control; analyses using mixed-effects models indicated that fisheries were less size selective in years when fish were larger than average and had lower exploitation rates. The observed harvest of larger than average sockeye salmon is consistent with the hypothesis that size-selective fishing contributes to decreasing age and length at maturation trends over time, but temporal variability in selection and strong disruptive selection suggests that the overall directional pressure is weaker than is often assumed in evolutionary models.     

Associations between the Alaska Steller sea lion decline and commercial fisheries.

The Steller sea lion (SSL) population in Alaska was listed as threatened under the Endangered Species Act in 1990. At that time, several procedural restrictions were placed on the commercial fisheries of the region in an effort to reduce the potential for human-induced mortality on sea lions. Several years have elapsed since these restrictions were put into place, and questions about their efficacy remain. In an effort to determine whether or not fisheries management measures have helped the SSL population to recover, estimates of the fishing activity of the Bering Sea/Gulf of Alaska commercial fisheries in the vicinity of individual SSL rookeries and SSL population trends at those rookeries were made using data from the National Marine Fisheries Service (NMFS) Fisheries Observer Program and Steller Sea Lion Adult Count Database. Fisheries data from 1976-2000 were analyzed in relation to SSL population counts from 1956-2001 at 32 rookeries from the endangered western stock. Linear regression on the principal components of the fisheries data show that a positive correlation exists between several metrics of historical fishing activity and the SSL population decline. The relationship is less consistent after 1991, supporting a hypothesis that management measures around some of the rookeries have been effective in moderating the localized effects of fishing activity on SSL.     

Directional selection by fisheries and the timing of sockeye salmon (Oncorhynchus nerka) migrations.

The timing of migration from feeding to breeding areas is a critical link between the growth and survival of adult animals, their reproduction, and the fitness of their progeny. Commercial fisheries often catch a large fraction of the migrants (e.g., salmon), and exploitation rates can vary systematically over the fishing season. We examined daily records of sockeye salmon (Oncorhynchus nerka) in the Egegik and Ugashik management districts in Bristol Bay, Alaska (USA), for evidence of such temporally selective fishing. In recent years, the early migrants have experienced lower fishing rates than later migrants, especially in the Egegik district, and the median migration date of the fish escaping the fisheries has been getting progressively earlier in both districts. Moreover, the overall runs (catch and escapement) in the Egegik district and, to a lesser extent the Ugashik district, have been getting earlier, as predicted in response to the selection on timing. The trends in timing were not correlated with sea surface temperature in the region of the North Pacific Ocean where the salmon tend to concentrate, but the trends in the two districts were correlated with each other, indicating that there may be some common environmental influence in addition to the effect of selection. Despite the selection, both groups of salmon have remained productive. We hypothesize that this resilience may result from representation of all component populations among the early and late migrants, so that the fisheries have not eliminated entire populations, and from density-dependent processes that may have helped maintain the productivity of these salmon populations.     

Long-term trends in the Australasian gannet (Morus serrator) population in Australia: the effect of climate change and commercial fisheries

The Australasian gannet (Morus serrator) population has increased considerably over the past century, both in New Zealand and Australia. Since 1980, the population in Australian waters has increased threefold, from 6,600 breeding pairs to approximately 20,000 pairs in 1999-2000, a rate of 6% per year. Reasons for the increase in the Australasian gannet population are poorly understood; here we consider the possible effects of recent fluctuations in climatic and oceanographic conditions, and changes in major local commercial fisheries. A significant trend towards more frequent, and stronger, El Niño Southern Oscillation events, warmer summer sea surface temperatures in Bass Strait, increased annual catches and catch per unit effort in the Victorian pilchard (Sardinops sagax) fishery and potential increased discarding of fisheries bycatch may account for at least some of the observed increase in the Australasian gannet population. The potential interactive effects of these factors on prey distribution and abundance and consequently on gannet numbers are discussed.     

Use of a seagrass residency index to apportion commercial fishery landing values and recreation fisheries expenditure to seagrass habitat service

Where they dominate coastlines, seagrass beds are thought to have a fundamental role in maintaining populations of exploited species. Thus, Mediterranean seagrass beds are afforded protection, yet no attempt to determine the contribution of these areas to both commercial fisheries landings and recreational fisheries expenditure has been made. There is evidence that seagrass extent continues to decline, but there is little understanding of the potential impacts of this decline. We used a seagrass residency index, that was trait and evidence based, to estimate the proportion of Mediterranean commercial fishery landings values and recreation fisheries total expenditure that can be attributed to seagrass during different life stages. The index was calculated as a weighted sum of the averages of the estimated residence time in seagrass (compared with other habitats) at each life stage of the fishery species found in seagrass. Seagrass‐associated species were estimated to contribute 30%–40% to the value of commercial fisheries landings and approximately 29% to recreational fisheries expenditure. These species predominantly rely on seagrass to survive juvenile stages. Seagrass beds had an estimated direct annual contribution during residency of €58–91 million (4% of commercial landing values) and €112 million (6% of recreation expenditure) to commercial and recreational fisheries, respectively, despite covering <2% of the area. These results suggest there is a clear cost of seagrass degradation associated with ineffective management of seagrass beds and that policy to manage both fisheries and seagrass beds should take into account the socioeconomic implications of seagrass loss to recreational and commercial fisheries.     

Preying on commercial fisheries and accumulating paralytic shellfish toxins: a dietary analysis of invasive Dosidicus gigas (Cephalopoda Ommastrephidae) stranded in Pacific Canada

In fall of 2009, several mass strandings of Humboldt squid (Dosidicus gigas) occurred on Vancouver Island (49°7′60N 125°54′0W). Morphological dissections coupled with DNA barcoding of stomach contents revealed Sardinops sagax (Pacific sardine) and Clupea pallasii (Pacific herring) as their primary prey. Plastic nurdles, fishing line, bull kelp, eelgrass, and a guillemot feather were also discovered. The primary prey, Pacific sardines and Pacific herring, are known to bioaccumulate paralytic shellfish toxins (PSTs); additionally, both PSTs and domoic acid (DA) have been implicated in other mass strandings. Therefore, stomach contents, and other tissues when possible, were tested for PSTs and DA. Testing revealed DA concentrations below regulatory guidance levels for human consumption, yet PSTs were well in excess. Though we cannot conclude that PSTs were the definitive cause of the strandings, our findings are the first report of PSTs in D. gigas.     

GIS and aquaculture: Assessment of soft-shell clam sites

The 1992 collapse of the northern cod fishery at Newfoundland, Canada and the subsequent closure of a majority of the inshore ground fishery has placed a focus on the development of aquaculture within the province. In May 1995 Innovative Fisheries Inc. of St. John's, Newfoundland, conducted field studies to evaluate the soft-shell clam (edible bivalve molluscs) resources on three sand flats near Burgeo, Newfoundland. GIS can be used to examine issues regarding the development and management of the soft-shell clam beds. GIS can also be applied to examine the issue of ‘competing uses’ for the proposed soft-shell clam aquaculture site. The information presented in this study indicates that GIS is an important tool for the aquaculture industry. These systems can be used to monitor, quantify and evaluate the soft-shell beds near Burgeo. Management issues such as water quality, resource sustainability as well as the economic viability of the clam resource can be assessed within a GIS environment. The results of the analysis in this study suggest potential problems with faecal coliform contamination from local cottages. Finally, data collection for aquaculture site assessment is required if a resource is to be managed effectively. GIS applications provide insights into the quality of the physical environment as well as the sustainability of a resource. However, it is the aquaculture operators who ultimately make the final decisions.     

Zooplankton fisheries of the world: A review

About 20 species of zooplankters (copepods, mysids, euphausiids, sergestids, and Scyphomedusae) are commercially fished and utilised as food or feed today. The annual world catch of crustacean zooplankton is probably a little less than 210,000 tons and accounts for 11% of the total crustacean catch in the world. The present status of plankton harvesting in various parts of the world is described. Problems in development of plankton fisheries are discussed.     

Aquaculture and the displacement of fisheries captures

In modern aquaculture, animal-production technology is used to increase aquatic food sources. Such controlled rearing of seafood can, in principle, shift the pressure off wild stocks and aquatic ecosystems by reducing fishing activities, which may advance marine conservation goals. We examined resource displacement—the reduced consumption of a resource due to its replacement with a more environmentally benign substitute—in fisheries. We employed panel regression techniques in an analysis of time-series data from 1970 through 2014 to assess the extent to which aquaculture production displaced fisheries captures for all nations for which data were available. We estimated 9 models to assess whether aquaculture production suppresses captures once other factors related to demand have been controlled for. Only 1 model predicted significant suppression of fisheries captures associated with aquaculture systems within nations over time. These results suggest that global aquaculture production does not substantially displace fisheries capture; instead, aquaculture production largely supplements fisheries capture.     

Taxing overexploited open-access fisheries: the role of demand elasticity

The paper aims at identifying the effects exerted by a tax levy on an overexploited and previously unregulated fishery. The analysis is carried out by means of a dynamic model that includes fish stock and harvesting effort as state variables. Attention is focused on the role played by demand elasticity which is shown to affect both transients and equilibria.According to the analysis, a levy induces a contraction in effort, which is sharper in the short term. As a consequence, the fish population recovers and ultimately settles at a higher equilibrium level. Therefore, a larger amount of fish is caught in the long run and sold at a lower price than in the unregulated setting. The more inelastic the demand, the smaller both the equilibrium price for fish and the tax imposed.     

Technological change and fisheries sustainability: The point of view of Adaptive Dynamics

The analysis of a simple model shows that exploitation of fish stocks can entrain in the long run the substantial decline or even the collapse of the stock, as well as difficulties in stock recovery, loss of fishery resilience, and reduction of the mean fish size. The results are in agreement with numerous observations, even though they are obtained with a simple model in which the harvesting fleet and the fish stock are considered as unstructured predator and prey. The study is carried out for the typical case of fleet dimension not too sensitive to the year-to-year fluctuations of the stock and assuming that the sole cause of evolution is technological innovation. The analysis is performed by means of Adaptive Dynamics, an approach born in theoretical biology which is used here in the context of technological change. Although the results are qualitatively consistent with those obtained long ago through the principles of bioeconomics, it is fair to stress that the underlying assumptions are different. In fact, in the bioeconomic approach fleet technology does not evolve and fishing effort varies to produce economic optimization, while in the Adaptive Dynamics approach technological innovation is the key driver. The paper is purely theoretical and the proposed model can hardly be tuned on any real fishery. No practical guidelines for managers can therefore be drawn, if not the general conclusion that long-term sustainability of exploited fish stocks can only be achieved if strategic parameters influencing technological change are kept under strict control.     

Conservation Easements: Biodiversity Protection and Private Use

Abstract:  Conservation easements are one of the primary tools for conserving biodiversity on private land. Despite their increasing use, little quantitative data are available on what species and habitats conservation easements aim to protect, how much structural development they allow, or what types of land use they commonly permit. To address these knowledge gaps, we surveyed staff responsible for 119 conservation easements established by the largest nonprofit easement holder, The Nature Conservancy, between 1985 and 2004. Most easements (80%) aimed to provide core habitat to protect species or communities on-site, and nearly all were designed to reduce development. Conservation easements also allowed for a wide range of private uses, which may result in additional fragmentation and habitat disturbance. Some residential or commercial use, new structures, or subdivision of the property were permitted on 85% of sampled conservation easements. Over half (56%) allowed some additional buildings, of which 60% restricted structure size or building area. Working landscape easements with ranching, forestry, or farming made up nearly half (46%) of the easement properties sampled and were more likely than easements without these uses to be designated as buffers to enhance biodiversity in the surrounding area. Our results demonstrate the need for clear restrictions on building and subdivision in easements, research on the compatibility of private uses on easement land, and greater public understanding of the trade-offs implicit in the use of conservation easements for biodiversity conservation.     

Sport and commercial fishing conflicts: A theoretical analysis

A recreational sector is added to a standard commercial fishing optimal control model to identify public decision variables which should be considered when determining optimal population levels and allocating harvestable fish between sport and commercial users. Both linear and nonlinear models are presented. A predator-prey relationship is also considered. Results derived from the models indicate that shortcomings exist with current economic inputs to policy making because of failure to consider relevant bioeconomic relationships. Future research topics to remedy this are discussed.     

Effects of economics and demographics on global fisheries sustainability

A good understanding of social factors that lead to marine ecological change is important to developing sustainable global fisheries. We used balanced panel models and conducted cross‐national time‐series analyses (1970–2010) of 122 nations to examine how economic prosperity and population growth affected the sustainability of marine ecosystems. We used catches in economic exclusive zone (EEZ); mean trophic level of fishery landings (MTL); primary production required to sustain catches (expressed as percentage of local primary production [%PPR]); and an index of ecosystem overfishing (i.e., the loss in secondary production index [L index]) as indicators of ecological change in marine ecosystems. The EEZ catch, %PPR, and L index declined gradually after gross domestic product (GDP) per capita reached $15,000, $14,000, and $19,000, respectively, and MTL increased steadily once GDP per capita exceeded $20,000. These relationships suggest that economic growth and biodiversity conservation are compatible goals. However, increasing human populations would degrade marine ecosystems. Specifically, a doubling of human population caused an increase in the %PPR of 17.1% and in the L index of 0.0254 and a decline in the MTL of 0.176. A 1% increase in human population resulted in a 0.744% increase in EEZ catch. These results highlight the importance of considering social and economic factors in developing sustainable fisheries management policy.     

The tragedy of the commons in international fisheries: An empirical examination

Historically, all capture fisheries have proven hard to manage; internationally shared stocks face an additional impediment to effective management. Previous fisheries studies estimate gains from cooperation for particular species or locations, but evidence is lacking on the wider effect that international sharing has in relation to other variables that affect stock status. This paper is an attempt to shed a broader light on the effect of sharing by identifying whether shared fish stocks are systematically more exploited. I compile exploitation status, biological and economic data into a unique two-period panel of more than 200 fish stocks from around the globe with which I test the theoretical implications of sharing. The empirical results from ordered category estimation suggest that shared stocks are indeed more prone to overexploitation.     

Biotic control of stream fluxes: spawning salmon drive nutrient and matter export

Organisms can control movements of nutrients and matter by physically modifying habitat. We examined how an ecosystem engineer, sockeye salmon (Oncorhynchus nerka), influences seasonal fluxes of sediments, nitrogen (N), and phosphorus (P) in streams of southwestern Alaska. The purpose of this study was to investigate whether salmon act as net importers or net exporters of matter and nutrients from streams and how these roles change as a function of salmon population density. We measured discharge and concentrations of suspended sediments and total N and P every 7-14 days for up to four summers in 10 streams spanning a gradient in salmon densities. We statistically allocated whole-season fluxes to salmon activities, such as excretion and bioturbation, and to export by hydrologic discharge. In addition, we used counts of spawning salmon to estimate nutrient and matter imports by salmon to streams. Large seasonal pulses of suspended sediments, P, and N were associated with salmon spawning activities, often increasing export an order of magnitude higher than during pre-salmon levels. Years and streams with more salmon had significantly higher levels of export of sediments and nutrients. In addition, years with higher precipitation had higher background export of P and N. Salmon exported an average of the equivalent of 189%, 60%, and 55% of total matter, P, and N that salmon imported in their bodies. The relative magnitude of export varied; salmon exported more than their bodies imported in 80%, 20%, and 16% across all streams and years for sediments, P, and N, respectively. A bioassay experiment indicated that the P exported by salmon is directly available for use by primary producers in the downstream lake. These results demonstrate that salmon not only move nutrients upstream on large spatial scales via their migration from the ocean and subsequent death, but also redistribute matter and nutrients on finer spatial scales through their spawning activities.