Letter: Public Has Right to Know How Fast Seal, Shark Populations are Growing

from James Kidney

Letter to the Editor:

The public needs to know how large the seal population is and how fast it is growing.  Although predatory sharks are now beginning to arrive in greater numbers, the seals are thriving and assuming control of major portions of Cape Cod's coastal waters and beaches.

There is a compelling need for researchers to undertake frequent population counts of grey and harbor seals inhabiting Cape Cod’s shorelines.  The most comprehensive method appears to be aerial surveys.  Funds for such research should be included in the forthcoming federal and/or state budget.

The largest grey seal population in the world is on Sable Island, 18 miles southeast of Halifax, Nova Scotia.  It grew from 500 seals a century ago to around 400,000 seals today. The recent growth rate is estimated to be around 13 percent per year.   Some of those seals have migrated to the USA, and they are creating a similar population explosion, mainly on public parkland.

Sable Island National Park is a narrow, crescent-shape sandbar with a surface area of about 13 sq. mi.    It is 26 mi. long, and only 0.93 mi. across at its widest point.  Grey seal counts from the 1960s estimated 200–300 pups were born annually at that time.   Surveys from 2003–2004 estimate the number of pups born in that season at 50,000.   It is believed 83,000 pups were born in 2016.  The island’s seals are sporadically preyed upon by shark species that inhabit the waters nearby.  Unusual 'corkscrew' bite wounds on dead seals suggest that large Greenland sharks are probably responsible for most attacks. 

The island has around 500 feral horses and a variety of birds, which are being crowded out by the seals.

The fishing industry has long complained about the volume of fish consumed by the seals.  Several years ago, the Government of Canada considered a controversial proposal to slaughter 220,000 grey seals on Canada's Sable Island.   To humanely control the surging population, the cull would involve shooting the animals in the head, thereby causing instant death, and then collecting them to be incinerated.  Some entrepreneurs have recommended ways to market the byproducts.

James Kidney, Truro


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