Managing the Black Sea Anchovy Fishery with Nutrient Enrichment and a Biological Invader

Many marine systems are subject to high nutrient loadings together with invasions by exotic species. Devising appropriate management responses is an increasing concern and one that has received relatively little attention from researchers. This paper considers the Black Sea anchovy fishery, which has benefited from the relaxation of a nutrient constraint, but has suffered from competition and predation by an invading comb-jelly (Mnemiopsis leidyi). We examine alternative hypotheses about the mechanism triggering outbreaks of the invader (sea temperatures versus nutrients), and the severity of these outbreaks, to see whether a constant escapement policy might be optimal for this fishery. If nutrient levels serve as the triggering mechanism, we argue a mixed blessing effect may be present, so that the effects of nutrient abatement for the anchovy fishery are uncertain. We specify our model empirically and show that a constant escapement policy would be viable under a scenario of reduced impacts from outbreaks of the invader and that nutrient abatement could be beneficial if nutrients trigger outbreaks.Mnemiopsis leidyi, nutrient abatement, stochastic bioeconomic model, biological invasion, Resource /Energy Economics and Policy, O3, O41, Q2, Q20, Q22,

Nutrient Enrichment and Marine Ecosystem Disturbance: A Deterministic and Stochastic Approach

Pollution of the marine areas that support much of the world's commercial fisheries is regarded as a pressing global environmental problem. One often-cited issue is nutrient enrichment, but this may be a mixed blessing: it contributes to primary productivity and increases the sustainable fish catch, while simultaneously causing occasional and damaging ecosystem events. Thus, enrichment's aggregate impact on the economic value of fisheries may be ambiguous. This research develops a method for analyzing such problems, using the example of the Black Sea anchovy fishery. Employing a bioeconomic model that incorporates nutrients directly into fish population dynamics, the problem is formulated in deterministic and stochastic terms and the results compared. The deterministic model assumes that nutrients only contribute positively to fish production for a given ecological state, and ignores stochastic events leading to shifts between states. Accordingly, marginal abatement of nutrients leads to annual welfare losses of US$ 45,000 to 713,00 per µ� (1989/90 prices), depending upon the ecosystem state. The stochastic formulation recognizes that planners may have some knowledge of potentially damaging shifts in ecological states, and wish to take this into account. When these shifts are related stochastically to the level of enrichment, nutrient abatement is shown to have an indeterminate welfare effect. However, an experimental empirical analysis indicates that a marginal change in nutrients can generate positive and sizeable aggregate benefits for the Black Sea anchovy fishery under certain conditions. The general applicability of such an approach for analyzing a range of marine environmental problems is noted

Local Fishing Communities and Nature Based Tourism in Baja, México: An Inter-Sectoral Valuation of Environmental Inputs

Nature-based tourism is often advocated as a desirable conservation strategy for smallscale fishing communities as it gives local people motivation to protect wildlife and ecosystems that attract visitors, while benefiting the community. However, valuation of environmental inputs in nature-based tourism, for instance charismatic species or scenic amenities, needs to be done correctly. Often, there are inter-sectoral costs and benefits involved that are not counted, so that determining the value of the environmental inputs to local communities may be more complex than simpler calculations might indicate. We model whales as an input to the production of wildlife viewing trips, but recognize that this occurs within a community dependent on a seasonal fishery. Standard theory suggests that industry will switch from fishing to whale watching every year when whale watching becomes marginally more profitable than fishing. We develop a simple theoretical model that allows us to analyze the interaction between the extractive and the non-extractive activities. As a case study, we use whale watching in the small coastal communities of the Bahía Magdalena lagoon complex in Baja, México.Alberto Ansuategi thanks financial support from the Ministerio de Economa y Competitividad (ECO-2015-68023) and the Eusko Jaurlaritza (IT-799-13 and MV-2017-1-0008)

International Veterinary Epilepsy Task Force recommendations for a veterinary epilepsy-specific MRI protocol

Epilepsy is one of the most common chronic neurological diseases in veterinary practice. Magnetic resonance imaging (MRI) is regarded as an important diagnostic test to reach the diagnosis of idiopathic epilepsy. However, given that the diagnosis requires the exclusion of other differentials for seizures, the parameters for MRI examination should allow the detection of subtle lesions which may not be obvious with existing techniques. In addition, there are several differentials for idiopathic epilepsy in humans, for example some focal cortical dysplasias, which may only apparent with special sequences, imaging planes and/or particular techniques used in performing the MRI scan. As a result, there is a need to standardize MRI examination in veterinary patients with techniques that reliably diagnose subtle lesions, identify post-seizure changes, and which will allow for future identification of underlying causes of seizures not yet apparent in the veterinary literature. There is a need for a standardized veterinary epilepsy-specific MRI protocol which will facilitate more detailed examination of areas susceptible to generating and perpetuating seizures, is cost efficient, simple to perform and can be adapted for both low and high field scanners. Standardisation of imaging will improve clinical communication and uniformity of case definition between research studies. A 6–7 sequence epilepsy-specific MRI protocol for veterinary patients is proposed and further advanced MR and functional imaging is reviewed