Sunday, November 19, 2017
MAKO SHARKS IN NEED OF STRICTER MANAGEMENT
I’m an active shark fisherman. I have been for decades. And though, over the years, I’ve caught, and helped other anglers to catch, a wide variety of species, here in the upper Mid-Atlantic, when you head out to do some shark fishing, you’re usually targeting makos.
They are an exciting fish to hook into. They’re fast, often fly out of the water in spectacular, tumbling leaps and can grow big enough to cause some serious sweat and pain before they’re finally brought alongside.
And they’re a good-looking fish, the embodiment of everything people first think of when they hear the word “shark;” sleek-bodied, with a pointed snout, strong lunate tail and a mouthful of teeth that resemble nothing so much as bent nails. Their indigo backs fade to silver-blue sides that flash as the fish rolls in the sunlit water, and when they roll next to the boat, they look up at you with the flat black eye of God.
Unfortunately, our North Atlantic makos seem to be in real trouble.
Looking back on my forty years in the fishery, it’s not hard to see the problem coming on. Over the years, I’ve seen the makos’ average size, abundance and season length shrink badly enough that I stopped bringing them home in 1997. Since then, every one that we’ve caught has been tagged and released, as part of the National Marine Fisheries Service’s Cooperative Shark Tagging Program. This fall, I had a chance to take the tagging process one step further, helping some researchers from Stony Brook University implant three makos with acoustic tags as part of a multi-year project.
For a long time, the available data suggested that makos were faring pretty well; the last stock assessment, conducted by the International Commission for the Conservation of Atlantic Tunas (which, despite its name, deals with shark and billfish issues as well) in 2012, found the stock to be healthy.
Unfortunately, that has now changed.
Based on the results of a satellite tagging study completed last summer, a team of scientists determined that a typical shortfin mako shark in the North Atlantic has only a 72% chance of surviving in the ocean for one year without being captured. That makes the likelihood of capture, probably but not necessarily by a pelagic longline vessel, about ten times greater than previously believed. The head of the research team was quoted by Sport Fishing Magazine explaining why the results of the satellite tagging study was so different from earlier tagging results.
“Traditionally, the data obtained to determine the rate of fishing mortality, a key parameter used to help gauge the health of shark stocks, has depended largely on fishermen self-reporting any mako sharks they may have caught. The challenge is that not all fishermen report the same way or some may underreport or not report their mako shark captures at all, so the these [sic] catch data are known to be of questionable reliability.”
The satellite tags, on the other hand, report in near real-time, and make it obvious that a shark has been caught and killed.
While the satellite tagging study has acknowledged limitations, since it was not originally designed to estimate mako shark mortality, was spatially limited to a section of the western Atlantic and may not represent what happens throughout the stock’s range, biologists have found the results worth further investigation.
ICCAT scientists, using unrelated data sets, have also come to believe that harvesting shortfin makos at the current rate will lead to a further decline in the North Atlantic population, and that fishing mortality would have to be reduced by nearly 80% to keep the stock from shrinking any more. However, such a reduction, to 1,000 metric tons, probably wouldn’t do much to rebuild the North Atlantic’s shortfin mako population. There is only a 25% chance that such a cut would halt overfishing and restore the stock to healthy levels of abundance by 2040.
ICCAT is now meeting to decide what management measures should be imposed on fishermen wishing to retain shortfin mako sharks in the North Atlantic. The ICCAT group considering the problem has noted that
“releasing animals brought to the vessel alive could be a potentially effective measure to reduce fishing mortality as studies indicate post-release survival is likely to be about 70%. Following best practices to correctly handle and release live specimens could therefore further increase post-release survival. However, at this time the Group does not have enough information to assess if the adoption of live releases alone will be enough to reduce landings to 1,000 t or less and stop further stock decline.”
A group of organizations concerned with the future of the shortfin mako, which includes Florida’s Mote Marine Laboratories, Oceana, the Pew Charitable Trusts, The Ocean Foundation, Shark Advocates International, and others, has written a letter to the National Marine Fisheries Service, asking that that the United States take a leadership role on the issue at the current ICCAT meeting. The letter read, in part,
“As you know, the new ICCAT population assessment for Atlantic shortfin mako sharks (Isurus oxyrinchus) has revealed alarming trends. In particular, the North Atlantic population has been significantly depleted, and overfishing continues. In order to have a reasonable chance (54% probability) of rebuilding by 2040, catches must be cut to zero. Accordingly, ICCAT’s Standing Committee on Research and Statistics (SCRS) has recommended a “complete prohibition on retention” as an immediate step to stop overfishing and begin the long recovery…
“With leadership from NMFS scientists, the SCRS Shark Working Group has conducted Ecological Risk Assessments (in 2008 and 2012) that rank shortfin mako high with respect to vulnerability to ICCAT fisheries. ICCAT has since banned retention of many other shark species, while skipping makos. Moreover, for nearly a decade, response to specific SCRS calls to cap or reduce mako fishing mortality has been wholly inadequate.”
Anyone familiar with how things work at ICCAT knows that scientists there rarely call for a complete prohibition on harvesting any fish that has commercial value, so when the SCRS makes such a recommendation with respect to North Atlantic makos, it’s a sign that tougher management measures are desperately needed.
Despite the need, there are undoubtedly a lot of people living on my stretch of coast who don’t want to see such a prohibition take place. Seafood dealers pay swordfish longliners well for their shortfin mako bycatch, and there are plenty of offshore anglers who look forward taking some mako steaks home for the grill. Shark tournaments are still big local events, and generate big dollars for the marinas and various organizations that sponsor and promote them; the money that competitors pay for dock space, fuel, food, fishing tackle, bait and chum goes directly to small businesses and boosts the economies of small coastal towns. Folks who profit from a fishery rarely if ever support shutting it down.
Such attitudes prevail in other nations, too, so a closure of the mako fishery will almost certainly face some level of international opposition. Thus, despite the scientific advice, it’s not at all certain that ICCAT will act to halt the mako’s decline. But it would be unfortunate if it did not.
There’s a trident-shaped scar on my right thumb, memorializing the day when a small female mako objected to my hand passing close to her face while I was setting her free. I salute her spirit. The beauty, the strength and the unpredictable speed of the mako are one of the recreational shark fishery's biggest attractions.
Which is reason enough to hope that ICCAT follows the science and does the right thing.