Terms of Reference

Indirect effects of bottom-contact fishing activities (by trap gear) on sponge reefs in the Strait of Georgia and Howe Sound

Regional Science Response Process – Pacific Region

March 2018
Nanaimo, British Columbia

Chairperson: Peter Chandler

Context

Glass (hexactinellid) sponge reefs have intrinsic, ecological, and economic value. They provide a link between benthic and pelagic environments, play an important role in carbon and nitrogen processing, and act as a silica sink. While a full understanding of their ecological role is yet to be realized, diverse communities of invertebrates and fish, including those of economic importance, have been documented in association with glass sponge reefs (Cook et al. 2008; Marliave et al. 2009; Chu and Leys 2010). There is evidence to suggest indirect effects of sediment (due to re-suspension) from human activities may impact sponge reef communities, including glass sponges (Leys 2013; Conway et al. 2001; Whitney et al. 2005; Conway et al. 2007; Yahel et al. 2007; Tompkins-MacDonald & Leys 2008). Note that the protection of sponge reefs is a key component to a number of international commitments made by Canada through the United Nations Convention on Biological Diversity and the United Nations Food and Agriculture Organization (FAO) Code of Conduct for Responsible Fisheries.

Since 2002, nine glass sponge reef complexes have been mapped by the Canadian Hydrographic Service in the Strait of Georgia and Howe Sound (Conway et al. 2004; Conway et al. 2005; Conway et al. 2007; Kim Conway, Natural Resources Canada, Sidney, BC, pers. comm.). Starting in 2014, DFO requested that fishers using bottom-contact gear (prawn trap, crab trap, shrimp trawl, groundfish trawl and hook-and-line) voluntarily avoid these nine areas while DFO consulted on formal protection measures.  Since that time, DFO has proceeded with formal fishery closures to protect these glass sponge reef complexes, including closures to First Nations Food, Social, and Ceremonial fisheries.

In 2012, an assessment was conducted of fisheries-induced re-suspended sediment impacts on Hecate Strait glass sponge reefs (Boutillier et al. 2013).  Using a pathway of effects (PoEs) model, this assessment identified the types of fishing activities likely to re-suspend sediment, and quantified the potential spatial extent of the resulting impacts.

Based on the previous assessment framework, Fisheries Management (Sustainable Fisheries Framework) Branch has requested Science Branch to identify the indirect effects of bottom-contact fishing activities by trap gear on the nine sponge reefs in the Strait of Georgia and Howe Sound.  This work focuses on the nine glass sponge reef complexes included in the current fishery closure process; other sponge reefs that may be found in the area and sponge formations (such as sponge gardens) are out of scope.

Objective

Using the methods and approach provided in Boutillier et al. (2013), the following Science Response will address the specific objectives as outlined below.

1. Provide estimates of remobilized sediment footprints resulting from bottom-contact trap gear fishing activities around the nine sponge reef complexes in the Strait of Georgia and Howe Sound.
2. Identify and discuss any knowledge gaps and/or uncertainties, including future work, identified through the application of this risk assessment method to the nine sponge reef complexes in the Strait of Georgia and Howe Sound.

Expected Publications

• Science Response

Expected Participation

• Fisheries and Oceans Canada (DFO): Science, Oceans, Fisheries Management -Sustainable Fisheries Framework

References

Boutillier, J., Masson, D., Fain, I., Conway, K., Lintern, G, O, M., Davies, S., Mahaux, P., Olsen, N., Nguyen, H. and Rutherford, K. 2013. The extent and nature of exposure to fishery induced remobilized sediment on the Hecate Strait and Queen Charlotte Sound glass sponge reef. DFO Can. Sci. Advis. Sec. Res. Doc. 2013/075. viii + 76 p.

Chu J.W.F., Leys, S.P. 2010. High resolution mapping of community structure in three glass sponge reefs (Porifera, Hexactinellida). Marine Ecology Progress Series. 417: 97-113.

Conway, K.W., Barrie, J.V., Krautter, M., 2004. Modern siliceous sponge reefs in a turbid  siliciclastic setting: Fraser River delta, British Columbia, Canada. Neues Jahrbuch für  Geologie und Paläontologie. 2004: 335-350.

Conway, K.W., Barrie, J.V., Krautter, M., 2005. Geomorphology of unique reefs on the western Canadian shelf: sponge reefs mapped by multibeam bathymetry. Geo-Marine Letters. 25: 205-213.

Conway, K., Krautter, M., Barrie, J.V. and Neuweiler, M. 2001. "Hexactinellid Sponge Reefs on the Canadian Continental Shelf: A Unique "Living Fossil"." Geoscience Canada 28(2): 71-78.

Cook S.E, Conway K.W., Burd, B. 2008. Status of the glass sponge reefs in the Georgia Basin. Marine Environmental Research. 66 (Suppl 1): S80–S86.

Leys, S.P. 2013. Effects of Sediment on Glass Sponges (Porifera,Hexactinellida) and projected effects on Glass Sponge Reefs. DFO Can. Sci. Advis. Sec. Res. Doc. 2013/074. vi + 23 p.

Marliave J.B., Conway, K.W., Gibbs, D.M., Lamb, A., Gibbs, C. (2009) Biodiversity and rockfish recruitment in sponge gardens and bioherms of southern British Columbia, Canada. Marine Biology. 156, 2247-2254.

Tompkins-MacDonald, G.J and Leys, S.P. 2008. Glass sponges arrest pumping in response to sediment: implications for the physiology of the hexactinellid conduction system. Marine Biology 154:973-984.

Whitney, F., Conway, K., Thomson, R., Barrie, V., Krautter, M., and Mungov, G. 2005. Oceanographic habitat of sponge reefs on the Western Canadian Continental Shelf. Continental Shelf Research. 25: 211-226.

Yahel, G., Whitney, F., Reiswig, H.M., Eerkes-Medrano, D.I., and Leys, S.P. 2007. In situ feeding and metabolism of glass sponges (Hexactinellida, Porifera) studied in a deep temperate fjord with a remotely operated submersible. Limnol. Oceanogr. 52(1): 428-440.