To deal with sharks, restore reef ecosystem

Years ago, at the University-Manoa’s Hawaii Institute of Marine Biology, I was fortunate to be a junior colleague of Dr. Albert Tester, who had led an early shark-culling effort, the "Billy Weaver Shark Research and Control Program" in 1959-1960. Subsequently, I was the principal investigator on several grants studying sharks in Hawaiian waters using long-lining from South Point to French Frigate Shoals.

A 1994 article published in Pacific Science, by Brad Wetherbee et al, reviewed shark-culling programs in Hawaii between 1959-1976. They reported that various programs caught a total of 4,668 sharks, of nine species including tiger sharks, at a rough cost of $182 per shark.

There was no conclusive demonstration that shark populations were reduced. Any change in shark populations would be inferred from reductions in catch per unit effort data.

Shark culling probably was not lastingly effective in Hawaii at the levels of fishing applied. But obviously, shark populations can be reduced (disastrously) with high levels of fishing. Witness the results of worldwide "shark finning." Hawaiian sharks now have state and federal regulations to protect their numbers. Any "culling" efforts would need special permission to kill sharks. In fact, presently, even live sharks cannot be collected for educational purposes such as display in public aquariums without such permission. (While it is the live shark that is collected, fins are attached to it and thus the prohibited "taking of fins" occurs.)

Since those brutal culling efforts, times have changed, for the better, and for the worse:

For the better because research techniques and technology now help us learn much about shark biology from living sharks — and preclude the old (in hindsight, barbaric) practice of killing sharks to get information from them. UH researchers are leading in the development and use of such techniques and deserve our commendation.

For the worse, because the reef ecosystems of Hawaii are severely diminished, under multiple stresses, and poorly managed.

Human intrusion on reef habitats has risen markedly as the numbers of visitors and locals residents increase and use intensifies.

Another change (a positive one, I believe) is the increased number of sea turtles, recovering from dangerously low population levels. Many blame this increase for the apparently high number of interactions between us and them (tiger sharks, mainly).

Diet studies in the main Islands and at French Frigate Shoals (a nesting ground for green sea turtles) revealed that turtle remains are found in the stomachs of tigers longer than 10 feet; smaller tigers ate reef fish and spiny lobsters.

I wish I shared George Burgess’s optimism expressed in last Sunday’s article about "the ocean returning to its natural state" with protection of marine species ("Swimming with sharks," Insight). However, in Hawaii at least, the current state of reef ecosystems, and the standing crops of prey items for most shark species, including lobsters and reef fish, are greatly diminished.

Here’s an idea, with equally little data to support it as the others on the list: Perhaps sharks are expanding their ranges in search of limited food, just as wolves, coyotes and mountain lions do in mainland suburbs and cities.

Predators do widen their ranges and increase search behavior when their habitat is disturbed. An upcoming significant disturbance in the Kaimana area will occur in the first week of 2016: The state Department of Land and Natural Resources will once again permit spearfishing there.

Look for more shark sightings then as reef fish, protected for two years, are harvested and blood flows in the water.

I suggest our best reaction to apparent increases in shark sightings and incidents is to work to restore our reef and ocean ecosystems to the healthy conditions that permit all users, including sharks and humans, to co-exist comfortably.