[Back to Program Search]
[Back to Schedule Listing]

C21
Fisheries, aquaculture and the oceans 4

Room: Salon G     Monday, August 1, 2016; 08:30 - 10:30

NB: Unless specified otherwise, presentation time slots are 15 minutes, and speed presentation times slots are 5 minutes. An asterisk * indicates the presenting author.

1.   08:30  Building a tool kit to assess reproductive performance of commercially exploited broadcast spawners inside and outside no-take zones . Bayer, SR *, Universtiy of Maine; Wahle, RA University of Maine; Brady, DC University of Maine; Jumars, PA University of Maine;

Abstract: In the US Northeast, area closures have been extremely successful in rebuilding and managing populations of the ocean scallop Placopecten magellanicus. One of the assumed benefits of marine reserves and fishing closures to broadcast spawning species such as scallops is to promote aggregations that maximize per capita reproductive rates through greater fertilization success. However, spawner-recruit relationships are generally not well quantified and fertilization rates have not been directly measured in situ. In this study we developed a tool to measure fertilization rates in situ and to explore the relationship between population density and fertilization success in scallops. We progressed from dockside trials to larger scale field manipulations of scallop aggregations on the sea bed. In both experiments we successfully detected male spawning events as measured by the fertilization rates of eggs in mesh chambers suspended in the water column. In our field plots, however, a 10-fold difference in adult density did not produce the expected difference in fertilization rate over the course of the spawning season. Having more direct empirical measurements of fertilization success will allow us to more directly test assumptions about reproductive performance of protected populations, thereby helping inform policy decisions regarding the efficacy of area closures in the management of free spawning marine species.

2.   08:45  A scientific approach to reducing the entanglement of right whales, and other marine wildlife, in Canadian commercial fishing gear. Brillant, S. *, Canadian Wildlife Federation; Wimmer, T. WWF-Canada; Rangeley, R. WWF-Canada; Taggart, C. Dalhousie University;

Abstract: The ability to predict where and when large marine wildlife become entangled in different types of fishing gear is important for developing conservation actions, and to be efficient, this knowledge needs to be scientifically sound. Recovery plans for North Atlantic right whales in both Canada and the USA specify the need to reduce or eliminate deaths caused by entanglement in fishing gear. Canada lags behind the USA in efforts to reduce this risk, but our research provides scientifically supported directions for action. We quantitatively predicted the locations and times where right whales encounter various types of fishing gear using a movement model, to estimate the locations of right whales, and the annual distribution of commercial fisheries. We show that the risk to right whales can be significantly reduced with minimal disruption to fisheries. Right whales in Canadian waters face most of the annual risk from fishing during July, August and September (12%, 49%, 38% respectively), and the groundfish fishery contributes most of this (86%). By restricting fishing in two specific high-risk locations, Canada can reduce risk to right whales by more than 30%, with negligible economic impact. Similar preliminary analyses for other species at risk will also be shown.

3.   09:00  Early evidence from the Chagos marine reserve sets baselines for tuna protection. Curnick, DC *, Zoological Society of London / University College London; Ferretti, F Stanford University; Koldewey, HJ Zoological Society of London; Jones, KE University College London / Zoological Society of London; Kemp, K Zoological Society of London; Collen, B University College London;

Abstract: The efficacy of very large marine protected areas (MPAs) for pelagic species is widely debated. The British Indian Ocean Territory (BIOT) was declared a no-take MPA in 2010. We quantified the spatial and temporal trends in catch per unit effort (CPUEs) of two target pelagic species, yellowfin and bigeye tuna, from the historical BIOT long line fisheries as a first step toward understanding the reserve's impact. To detect any effects of the reserve establishment on tunas, Indian Ocean Tuna Commission (IOTC) long line data were analysed to compare CPUEs in the areas around BIOT. CPUE of yellowfin in BIOT declined steadily from 1993 to 2010, with a strong seasonal signature. In contrast, CPUE of bigeye showed a slight increase over the same period. Yellowfin catches were concentrated in space and time around the atolls and islands, whilst bigeye were more prevalent in deeper water. Fishing effort declined in the area around BIOT since reserve establishment. Standardised yellowfin CPUEs declined markedly in the region immediately surrounding BIOT, in contrast to a slight increase in standardised bigeye CPUEs. CPUEs for both species rose sharply immediately after the reserves establishment before swiftly falling to below pre-reserve levels as the fishery rapidly absorbed any potential spill over effects from the reserve. These results suggest that to protect mobile species such as tuna, MPAs should be established in conjunction with other fisheries management interventions.

4.   09:15  Tracking global fishing from space. Boerder, K. *, Dalhousie University; Worm, B. Dalhousie University;

Abstract: A key challenge in contemporary ecology and conservation is to accurately track the spatial distribution of human impacts, such as fishing. Better understanding of the behavior of the global fishing fleets especially in remote areas like the High Seas is required to prioritize and enforce fisheries management and conservation measures worldwide. Satellite-based Automatic Information Systems (S-AIS) are installed on most ocean-going vessels and are considered a novel tool to explore the movements of fishing fleets. I present three approaches to identify fishing activity for three dominant fishing gear types: trawl, longline and purse seine. Using a large dataset containing S-AIS vessel tracks from 2011 until present, we developed methods to detect fishing activities worldwide: for trawlers we produced a Hidden Markov Model using vessel speed as observation variable. For longliners we designed a Data Mining approach using an algorithm inspired from studies on animal movement. For purse seiners a multi-layered filtering strategy was implemented. Validation against expert-labeled datasets showed average detection accuracies of 83% for trawler and longliner, and 97% for purse seiner. Our study represents the first comprehensive approach to detect potential fishing behavior on a global scale. This work highlights the global movements of individual vessels and will help to make fisheries activities fully transparent to ocean scientists, managers and the public.

5.   09:30  Alternate stable states in coupled fi shery-aquaculture systems. Orobko, MK *, University of Toronto, Department of Ecology & Evolutionary Biology; Krkošek, M University of Toronto, Department of Ecology & Evolutionary Biology; Molnar, PK University of Toronto Scarborough, Department of Biological Sciences;

Abstract: Stagnating capture fisheries production has led to rapid aquaculture development in marine ecosystems. Farmed fish can have negative ecological effects on nearby wild fish and these populations can interact economically by supplying similar products to the market. Theory to explain how these interactions affect fishery-aquaculture population dynamics and system resilience is lacking. We developed mathematical models of wild and farmed fish dynamics that integrated market interactions, current management approaches, and a negative ecological effect of farmed fish on wild fish. We demonstrate that alternate stable states and hysteresis can exist in response to demand for fish, indicating decreased system resilience. Critical transitions from a capture fishery-dominated state to an aquaculture-dominated state with few or no wild fish can occur that are difficult to reverse. The existence of alternate stable states and the severity of hysteresis is highly dependent on the strength of the ecological effect of farmed fish on wild fish. Global salmonid capture fisheries and aquaculture production data indicate that alternate stable states may structure transitions from fisheries to aquaculture, in addition to conventional fisheries dynamics. Managers of coupled fishery-aquaculture systems should consider the potential ecological consequences of alternate stable states and that ecological effects of farmed fish on wild fish strongly influence the sustainability of aquaculture growth.

6.   09:45  Factoring natural disasters into small-scale fisheries' management. Claydon, JAB *, Department of Environment & Maritime Affairs, Turks & Caicos Islands Government; Calosso, MC Department of Environment & Maritime Affairs, Turks & Caicos Islands Government;

Abstract: Periodic natural disasters such as hurricanes are inevitable for most tropical coastal nations. Hurricanes affect local stocks of harvestable marine products in various and possibly predictable ways. A species' life history plays a large role in determining the nature of any impact and the time-scale of recovery. In addition, natural disasters disrupt the socio-economic structure of coastal communities and may lead to increased pressure on fisheries while other industries such as tourism recover. However, small-scale fisheries management does not often account for natural disasters adequately. The Turks and Caicos Islands (TCI) is a major regional exporter of spiny lobster (Panulirus argus) and queen conch (Strombus gigas), with a predominantly local market for various reef fishes including groupers, snappers, and grunts. We used the fisheries of the TCI to illustrate characteristic stock responses (both documented and projected) to hurricanes. Many of these species have life-histories that display ontogenetic shifts in habitat that lead to increased vulnerability to hurricanes during juvenile stages. The stock response may therefore be felt by fisheries some years after the hurricanes. Management strategies designed to limit the ecological and social impacts of hurricanes to local fisheries include efforts to increase ecosystem resilience to hurricanes generally, but also building the stocks' capacities to endure a temporary spike in fishing pressure.

7.   10:00  Q&A Session.





[back to schedule]