Browsing by Subject "ecosystem-based fisheries management"

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    ItemOpen Access
    EVALUATING TRADE-OFFS IN AN ECOSYSTEM-BASED FISHERY MANAGEMENT PARADIGM: AN EXPLORATION THROUGH ANALYSIS OF THE ATLANTIC BUTTERFISH AND LONGFIN SQUID FISHERIES
    (2013-04-25) Rogers, Anthony; Carlisle, Keith; Wang, Jiaxi
    The Mid-Atlantic Fishery Management Council, our client for this masters project, is evaluating how best to transition from a primarily single-species management approach to an integrated multi-species management paradigm. In this connection, we explore how economic considerations may be incorporated into an integrated multi-species management approach by focusing on two closely associated stocks managed by the Council: longfin squid and Atlantic butterfish. We take several different approaches in our analysis of the two fisheries, our ultimate objectives being (i) to characterize the behavior of the fleets based upon historical landings data and geospatial analysis; and (ii) to provide the Council with insight into the potential impact of management constraints and ecosystem interactions on economic benefits in the fisheries. To illustrate potential impacts to economic benefits, we develop a two-species bioeconomic model and derive optimal harvest levels for the stocks, taking into account varying degrees of management constraints and ecosystem interactions. Based upon our analysis of landings data, we found that the Council’s allocation of the longfin squid landings quota among trimester management periods is no longer representative of actual landings in the fishery throughout the year. As a result, there is potential that the fishery may be forced to close prematurely in the summer months, thereby reducing economic benefits to participants who are highly dependent on revenues from the fishery. We also found, based upon our geospatial analysis of butterfish landings and butterfish bycatch in the longfin squid fishery, that a statistically significant correlation exists between the distance to shore from the point of catch and the butterfish bycatch rate. With respect to the model, we explored the importance of three parameters not generally included in a single-species model: predation, bycatch by fishermen, and benefits to the longfin squid population of additional butterfish. We found that all three have potential economic impacts. We also found that the amount of the total allowable catch of butterfish allocated to a bycatch cap imposed on the longfin squid fishery is higher than necessary to prevent early closure of the longfin squid fishery and could result in lost revenues in the butterfish fishery.
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    ItemOpen Access
    On the dynamic management of marine resources
    (2014) Dunn, Daniel Carl

    Mismatches in the spatiotemporal variability of resource, resource users and management actions breeds inefficiency in the management of marine resources. To date, the spatiotemporal resolution and extent of fisheries management has been largely dictated by logistical and political constraints, and secondarily by the geographic range of the species or meta-population dynamics. Management units are rarely smaller than 1000 km2 in developed coastal fisheries, and management measures generally occur at resolutions larger than 100 km2. From a temporal perspective, the finest resolution of management measures is at best a month but more generally a year. As such, attempts to manage processes and patterns at sub-10 km, sub-1 month resolution often involve some level of spatiotemporal mismatch. To address the obvious spatiotemporal mismatch between a dynamic ocean and static management, to allow for a comprehensive implementation of ecosystem-based fisheries management, and to minimize inefficiency in our management of marine resources, we must seek to develop more dynamic management measures that allow managers to address scales, processes and patterns occurring under ten kilometers.

    In this dissertation I apply point pattern processes, cumulative distribution functions, receiver operator characteristic curves, simulated annealing tools, regression models and clustering techniques to develop examples of two dynamic management measures and to compare the efficiency of static versus dynamic management measures. I show that autocorrelation analysis can inform the distances and times used in real-time closures based on move-on rules. Further, I identify optimum bottom temperature threshold values to separate individual species within the Northeast Multispecies Fishery from Atlantic cod. Results demonstrate that dynamic spatiotemporal management measures are widely applicable, and more effective and more efficient than static time-area closures. Unexpected trends in some results due to a changing climate indicate possible increasing thermal overlap between Atlantic cod and many other species in the fishery. Implications of scale in fisheries management and the importance of coarse scale (1 - 10km) ecological patterns to fisheries are discussed.