THE U.S. DAIRY INDUSTRY

Agribusiness,

A TRADE LIBERALIZATION IN INTERNATIONAL DAIRY MARKETS

International dairy industries remain among the most distorted agricultural sectors. Dairy average bound tariffs remain among the highest of all agricultural commodities, and dairy trade is characterized by a large number of megatariffs and tariff-rate quotas (TRQs). The objective of our study is to examine how the international dairy markets might respond to policy changes under various assumptions, using a partial equilibrium, multiple-commodity, multiple-region model of agricultural policy and trade. Our results indicate that liberalization will reduce supplies, increase dairy trade, and raise world prices.Dairy Markets, Trade Liberalization, Model, Policy, International Relations/Trade,

Population dynamics of a commercially harvested, non-native bivalve in an area protected for shorebirds: Ruditapes philippinarum in Poole Harbour, UK

The Manila clam Ruditapes philippinarum is one of the most commercially valuable bivalve species worldwide and its range is expanding, facilitated by aquaculture and fishing activities. In existing and new systems, the species may become commercially and ecologically important, supporting both local fishing activities and populations of shorebird predators of conservation importance. This study assessed potential fishing effects and population dynamics of R. philippinarum in Poole Harbour, a marine protected area on the south coast of the UK, where the species is important for oystercatcher Haematopus ostralegus as well as local fishers. Sampling was undertaken across three sites of different fishing intensities before and after the 2015 fishing season, which extends into the key overwintering period for shorebird populations. Significant differences in density, size and condition index are evident between sites, with the heavily dredged site supporting clams of poorer condition. Across the dredge season, clam densities in the heavily fished area were significantly reduced, with a harvesting efficiency of legally harvestable clams of up to 95% in this area. Despite occurring at significantly higher densities and growing faster under heavy fishing pressure, lower biomass and condition index of R. philippinarum in this area, coupled with the dramatic reduction in densities across the fishing season, may be of concern to managers who must consider the wider ecological interactions of harvesting with the interest of nature conservation and site integrity

Impacts of a novel shellfishing gear on macrobenthos in a marine protected area: pump-scoop dredging in Poole Harbour, UK

Understanding the impact of bottom-fishing gears at various scales and intensities on habitats and species is necessary to inform management. In Poole Harbour, UK, a multiple use marine protected area, fishermen utilise a unique ̋“pump-scoop” dredge to harvest the introduced Manila clam Ruditapes philippinarum. Managers need to balance the socio-economic benefits of the fishery with ecological concerns across the region, which has required a revision of by-laws that include both spatial and temporal measures. Within an operational fishery, we used a Before-After-Control-Impact sampling design to assess the impacts of pump-scoop dredging on benthic physical characteristics and community structure in an area where there was no dredging, an area newly opened to dredging and an area subject to high levels of historic dredging. A sampling grid was used in each area to best capture any fishing effort in the newly opened area. Core samples were taken to a depth of 30 cm within intertidal mudflats. A significant loss of fine sediments was observed in the site subject to high intensity dredging and a significant change in community structure also occurred in both dredged sites throughout the study period. In the newly opened site this was characterised by a relative increase in species richness, including increased abundance of annelid worms, notably Hediste diversicolor and Aphelochaeta marioni and a decline in the abundance of the bivalve mollusc Abra tenuis. These changes, albeit relatively small, are attributed to physical disturbance as a direct result of pump-scoop dredging, although no difference in the classification of the biotope of the site was observed. This is of particular interest to managers monitoring site condition within areas under the new by-laws as the Manila clam is spreading to other protected estuaries in the region

Acid secretion by the boring organ of the burrowing giant clam, Tridacna crocea

The giant clam Tridacna crocea, native to Indo-Pacific coral reefs, is noted for its unique ability to bore fully into coral rock and is a major agent of reef bioerosion. However, T. crocea\u27s mechanism of boring has remained a mystery despite decades of research. By exploiting a new, two-dimensional pH-sensing technology and manipulating clams to press their presumptive boring tissue (the pedal mantle) against pH-sensing foils, we show that this tissue lowers the pH of surfaces it contacts by greater than or equal to 2 pH units below seawater pH day and night. Acid secretion is likely mediated by vacuolar-type H+-ATPase, which we demonstrate (by immunofluorescence) is abundant in the pedal mantle outer epithelium. Our discovery of acid secretion solves this decades-old mystery and reveals that, during bioerosion, T. crocea can liberate reef constituents directly to the soluble phase, rather than producing sediment alone as earlier assumed

Reference points for predators will progress ecosystem-based management of fisheries.

Ecosystem-based management of fisheries aims to allow sustainable use of fished stocks while keeping impacts upon ecosystems within safe ecological limits. Both the FAO Code of Conduct for Responsible Fisheries and the Aichi Biodiversity Targets promote these aims. We evaluate implementation of ecosystem-based management in six case study fisheries in which potential indirect impacts upon bird or mammal predators of fished stocks are well publicized and well studied. In particular we consider the components needed to enable management strategies to respond to information from predator monitoring. Although such information is available in all case studies, only one has a reference point defining safe ecological limits for predators and none has a method to adjust fishing activities in response to estimates of the state of the predator population. Reference points for predators have been developed outside the fisheries management context but adoption by fisheries managers is hindered a lack of clarity about management objectives and uncertainty about how fishing affects predator dynamics. This also hinders the development of adjustment methods because these generally require information on the state of ecosystem variables relative to reference points. Nonetheless, most of the case studies 58 include precautionary measures to limit impacts on predators. These measures are not used tactically and therefore risk excessive restrictions on sustainable use. Adoption of predator reference points to inform tactical adjustment of precautionary measures would be an appropriate next step towards ecosystem-based management

Communicating complex ecological models to non-scientist end users

Complex computer models are used to predict how ecological systems respond to changing environ- mental conditions or management actions. Communicating these complex models to non-scientists is challenging, but necessary, because decision-makers and other end users need to understand, accept, and use the models and their predictions. Despite the importance of communicating effectively with end users, there is little guidance available as to how this may be achieved. Here, we review the challenges typically encountered by modellers attempting to communicate complex models and their outputs to managers and other non-scientist end users. We discuss the implications of failing to communicate effec- tively in each case. We then suggest a general approach for communicating with non-scientist end users. We detail the specific elements to be communicated using the example of individual-based models, which are widely used in ecology. We demonstrate that despite their complexity, individual-based models have characteristics that can facilitate communication with non-scientists. The approach we propose is based on our experiences and methods used in other fields, but which until now have not been synthesised or made broadly available to ecologists. Our aim is to facilitate the process of communicating with end users of complex models and encourage more modellers to engage in it by providing a structured approach to the communication process. We argue that developing measures of the effectiveness of communication with end users will help increase the impact of complex models in ecology

Can sacrificial feeding areas protect aquatic plants from herbivore grazing? Using behavioural ecology to inform wildlife management

Effective wildlife management is needed for conservation, economic and human well-being objectives. However, traditional population control methods are frequently ineffective, unpopular with stakeholders, may affect non-target species, and can be both expensive and impractical to implement. New methods which address these issues and offer effective wildlife management are required. We used an individual-based model to predict the efficacy of a sacrificial feeding area in preventing grazing damage by mute swans (Cygnus olor) to adjacent river vegetation of high conservation and economic value. The accuracy of model predictions was assessed by a comparison with observed field data, whilst prediction robustness was evaluated using a sensitivity analysis. We used repeated simulations to evaluate how the efficacy of the sacrificial feeding area was regulated by (i) food quantity, (ii) food quality, and (iii) the functional response of the forager. Our model gave accurate predictions of aquatic plant biomass, carrying capacity, swan mortality, swan foraging effort, and river use. Our model predicted that increased sacrificial feeding area food quantity and quality would prevent the depletion of aquatic plant biomass by swans. When the functional response for vegetation in the sacrificial feeding area was increased, the food quantity and quality in the sacrificial feeding area required to protect adjacent aquatic plants were reduced. Our study demonstrates how the insights of behavioural ecology can be used to inform wildlife management. The principles that underpin our model predictions are likely to be valid across a range of different resource-consumer interactions, emphasising the generality of our approach to the evaluation of strategies for resolving wildlife management problems