Monday 30. April 2012

Environmental Impact of Scallop Dredging

On Wednesday, May 2, Megan Chen will present her master's thesis in Coastal and Marine Management titled The environmental impact of scallop dredging in Breiðafjörður, West Iceland: A call for fishing technique and management reform.

Megan's thesis advisor is dr. Jónas Páll Jónasson, specialist at the Marine Research Institute Iceland, and her reader is Vincent Gallucci, professor of Aquatic and Fishery Siences at the University of Washington and a visiting researcher at the University Centre of the Westfjords.

The presentation starts at 16:00 in room 1-2 at the University Centre and everyone is welcome to attend.

The fishery for C. islandica in Breiðafjörður was closed in response to the stock collapse around 2003. High rates of natural mortality, an increase in sea surface temperature, and inability to endure fishing pressure have been mechanisms suggested for the collapse. The environmental impact of roller dredging was examined in two ways: (1) a framework for assessing cumulative impact on vulnerable marine taxa, and (2) modeling the effects on yield per recruit with the inclusion of different levels of indirect mortality. Results showed that total historical cumulative impact was highest for maerl (35.25%), echinoidea (35.25%), bivalves (33.24%) and alcyonacea (30.85%). As well, peak yield per recruit with the addition of indirect fishing mortality of 0.155 dropped to 27% of peak yield per recruit with no indirect fishing mortality. The certainty and significance of these results are discussed, along with strengths and weaknesses of both methods used. Then, a list of criteria was developed for fishing technique transform, and management actions are suggested.

Photo: Acélan.

Chlamys islandica. Photo: Acélan, from Wikipedia.
Chlamys islandica. Photo: Acélan, from Wikipedia.