Sardine Harvest a Threat to Humpbacks?

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Whalers killed the last humpback whale in the Georgia Strait off the mouth of the Fraser River in 1907. Now, the humpbacks are returning to the Strait, and to other British Columbia (Canada) waters, reports BC newspaper The Tyee.

But whale researchers and whale watching operators are questioning whether a revival of a different kind – an expanded fishery for pilchards (Pacific sardines) mandated this year by the Department of Fisheries and Oceans (DFO) – could threaten the return of the humpbacks,

Both the humpbacks and the pilchards have been observed in increasing abundance along the BC coast in recent years. The humpbacks are a particular boon to the whale watching industry along the coast, as their dramatic breaching behaviour, long, wing-like fins and dramatic “lunge feeding” combine to make the 40-ton leviathans among the most picturesque of the world’s whales.

The humpback was hunted to near extinction during the 20th century. Currently, the humpback population of the North Pacific is estimated around ten thousand animals, up from a remnant population of only a thousand whales when whaling stopped in the 1960s.

Many observers link their reappearance along BC’s coast to the comeback of pilchard populations over the same time span. Researchers are still investigating the relationship between pilchards and humpback whales, but many believe that the small fish make up an important element in the marine mammals’ diet.

Ramped up catch limits

Pilchards, which once sustained a major fishing industry from Mexico to Alaska (and fed the canning industry John Steinbeck portrayed in Cannery Row) had almost disappeared by the end the 20th century, in part because of over-fishing and in part because of poorly understood natural cycles of abundance. At any rate, the pilchards are back in large numbers along our coastline, and the humpbacks seem to have come back with them.

The Department of Fisheries and Oceans has been gradually ramping up a commercial fishery on the increased pilchard stocks since 2002, and for the 2005 season (set to run from July 11 of this year until Feb. 9 of 2006 along the BC coast) the number of boats licensed to fish for pilchard has been doubled from last year’s 25 to 50 for this season, with a maximum catch of 17,903 metric tones of fish to be taken.

Dr. Jim Darling, a whale scientist with the Pacific Wildlife Foundation, told The Tyee he is worried that this expanded fishery could drive humpbacks out of BC waters to areas where their food supply is more abundant.

Fears of net entanglements

“There is very limited scientific information available to define the extent of this conflict,” Darling said. “However, it is quite clear the behaviour of the humpbacks is tied to the abundance and behaviour of the fish. There is not only a potential conflict over the resource, but also, if fishing is allowed amongst the whales, the potential for net entanglements increases – a significant problem in other parts of the world.”

Darling warned that imprudent expansion of the fishery could damage local whale watching, a multi-million dollar eco-friendly business helping to shore up economies of small towns on the outer coast of Vancouver Island.

DFO spokespeople say Darling has nothing to worry about. Sandy McFarlane, a sardine expert with the Department, told The Tyee that the 2005 opening on pilchards, even with twice as many boats on the water, is still a very small fishery. “The size of this fishery would not have any impact on humpback whales,” he said.

Lisa Miachika, Pelagic Resource Manager for DFO on the Pacific coast told The Tyee. the Department was sure that there was enough pilchard biomass in BC waters to support the proposed fishery.

“We are expanding this fishery very slowly,” she said. “We certainly wouldn’t say that this represents over-fishing. We don’t see any conflict at this time.”