Pacific Shark Populations In Decline: new study provides hard numbers on pelagic species

The results of a recent study published in Conservation Biology paints a disturbing picture of ongoing decline of sharks in the Pacific Ocean.  Now, to many who are familiar with the subject of shark finning and overfishing, this does not necessarily sound, unfortunately, like anything new - it is what many of us have been fighting about for some time.  However, it's an important report because it covers a wide period of time, has specific numbers, and notes that some areas in shark conservation that receive considerable public support may not be as effective as hoped.

The study by the Secretariat of the Pacific Community in New Caledonia, headed up by Dr. Shelley Clark, covers a fifteen-year period, examining catch records from several fisheries throughout the Pacific, and shows significant declines in the catch rates for blue, mako, oceanic whitetip sharks, along with declining average size in oceanic whitetip and silky sharks (following the same fate of tuna and billfish).  These are all, basically, pelagic or open water sharks that operate outside of most national ocean boundaries in international waters.

Oceanic whitetips were shown to be declining annually at a rate of 17%.  Based on just that number alone, that would mean that oceanic whitetips in Pacific waters have 5-6 years left.  Unfortunately, that could be accelerated because of how animal populations can reach a "tipping point" where their declining numbers can no longer be supported by any means of natural reproduction and the population suddenly collapses and they plummet to oblivion.

Blue sharks were also reported to be declining at a rate of 5% in the North Pacific.  Blue sharks are a bit more abundant and more productive, but they, along with the oceanic whitetip are highly sought after by commercial shark fishing operations.  Physically, these two species have particularly large pectoral fins so, quite literally, fishermen get more bang for the buck with a shark with large fins, in open international waters and, at least with the blue shark, are slightly more abundant.

The New Caledonia study goes on to report that, in international waters, shark fishing for fins or the entire carcass, has proved to be a difficult practice to regulate due to insufficient enforcement, complex laws regarding fin-to-carcass ratios (the result of compromises by international agencies to commercial interests), and no follow-through enforcement or prosecution at the domestic level.  And then there is the impact of illegal fishing or longline fishing where numbers of sharks are caught but were not necessarily targeted.  Time and time again, we find that laws or regulations that are in place mean nothing if there is insufficient enforcement and prosecution.  Pardon the pun, but too often the laws have no teeth.

As reported in a recent press release, Sonja Fordham, president of Shark Advocates International, had this to say about the report and the current state of regulations, "These findings underscore conservationists' messages that most finning bans are not properly enforced, and alone are not sufficient to reverse shark population declines.  Prohibitions on at-sea removal of shark fins not only bolster finning ban enforcement, but also facilitate collection of species-specific fisheries data that are key to refining population assessments and informing the establishment of urgently needed shark catch limits."

This is why it is critical for all shark conservationists to focus some of their interest, energy, and passion into prodding and supporting those organizations that work on behalf of sharks in the international arena.  It may seem a bit removed and you may feel a bit ineffectual compared to regional efforts like state or local shark finning or fishing bans, but, remember, most of the ocean is in international jurisdiction.  If we do not pressure these worldwide agencies to act responsibly, based on current scientific information, then we will find ourselves putting band aids on our local waters, while the open oceans are hemorrhaging badly.

Source: PRNewsire       

Turtles and Sharks: long migrations studied in the South Atlantic

Animal migration is one of nature's most mysterious presentations of animal behavior. What makes an animal travel great distances? How are they able to do it in a relatively straight path? Why do they use the same route year after year? Just how are they so good at it, while I can get lost in the local Costco?

One vast body of water where several marine species migrate but where mankind has not spent much time studying these movements is the South Atlantic, between South America and Africa. However, two recent studies have shed some interesting light on the long migration paths taken by leatherback turtles and blue sharks. Both of these species are threatened with possible extinction, so the more we know, the better we can manage our conservation efforts.

As reported in the Proceedings of the Royal Society B, researchers from England tagged and track the migratory routes of leatherback turtles for five years, from a breeding colony in Central Africa to feeding grounds in the southwestern Atlantic. Using satellite tracking tags on 25 females, the researchers found that the turtles followed three migratory paths, often traveling in remarkably straight lines.

One female turtle was tracked along a path that totaled just under 4,700 miles and took about 150 days of nonstop swimming to complete. The researchers are keen to know the "when and where" of these journeys to ensure that commercial fisheries do not take advantage of the turtle's singular purpose and place themselves right in the turtles' paths. The researchers are hoping to avoid a large decline in leatherback turtles in the South Atlantic as has happened to leatherbacks in the Pacific.

"All of the routes we've identified take the leatherbacks through areas of high risk from fisheries, so there's a very real danger to the Atlantic population," said University of Exeter professor Brendan Godley.

At the same time, researchers from the University of Florida were tracking the migratory routes of the blue shark. Working with a Brazilian team of researchers, Felipe Carvalho, under the supervision of renown shark expert Dr. George Burgess, Director of the Florida Program for Shark Research, began tagging blue sharks along the Brazilian coast. The question was whether the tracking results would show a migration that would link shark populations in both the southeastern and southwestern Atlantic.

Blue sharks are heavily fished in the South Atlantic and within coastal territorial waters some nations are trying to determine how to best manage the remaining populations. By showing a migratory link between these separate locations, it emphasizes the need for multinational cooperation. As it turned out, one of Carvalho's blue sharks, tagged off the coast of Brazil, was detected off Africa 87 days later.

“This is the first evidence of the transatlantic migration of a blue shark from the southwestern Atlantic Ocean to the southeastern Atlantic Ocean. We thought this migration might be happening, but we never had the data before to prove it,” Carvalho said.

More and more, we are finding species that travel along oceanic highways, making incredible journeys over and over again. Navigating by prevailing currents, or visual cues, or even by the Earth's magnetic fields - all have been suggested as possible theories that could account for the animal's amazing accuracy.

Whatever the method, it is important for us to understand these migrations and their purpose and use that knowledge to protect rather than take advantage of leatherback turtles, blue sharks, and so many other species that roam the seas.

Read about tracking leatherback turtles from the Associated Press.
Read about tracking blue sharks from Physorg.com

Oceanic White Tip Sharks: curious pelagic predators with an unfair reputation

A sleek but muscular body gliding effortlessly through cobalt blue water, its rounded snow-capped dorsal fin slicing the water just below the surface, the Oceanic White Tip Shark is one of the premier pelagic (open ocean) predators.

Beqa Adventure Divers's blog picked up on a series of terrific photos of oceanic white tips, posted by LupoDiver on a recent South Atlantic trip with Jim Abernethy's Scuba Adventures.

Oceanic white tip sharks are important open ocean predators and scavengers. As with most other sharks, they play a critical role in keeping the oceanic backyard clean and the populations of their prey healthy by culling the weak, injured, and sick. They are intensely curious as they do not live in a world of wall-to-wall animals, so anything that catches their attention either visually or by scent is quickly investigated.

Unfortunately, these sharks also have a bad reputation carried down through history as a man-eater. Often attracted by the low frequency sounds given off by sinking ships (not your typical underwater background noise), particularly from sinking warships, these sharks were known to attack sailors in the water - their hunting/scavenging instincts piqued by blood from wounded sailors. Sadly, what began as natural curiosity and a reaction to food stimulus in a limited-prey environment turned into a fearsome oceanic killer reputation. Turn down the anxiety level a few notches and you get a lot closer to the truth, as LupoDiver and his fellow divers discovered on their trip.

Beqa Adventure Diver also comments on LupoDiver's picture of a blue shark, another pelagic predator whose numbers have dropped considerably over the years, a favorite target for the commercial shark fisheries.

My first unexpected encounter with a shark in open water was with a beautiful blue shark, over 20 years ago, off Santa Cruz Island which is part of California's Channel Island chain. Following that, my first cage diving experience was being surrounded by a group of blue sharks. Now, Southern California's blue shark diving operations have all but disappeared and, sadly, I suspect I may never come across another blue shark without a lot of chumming and patience.

LupoDiver, treasure your experience with the oceanic white tip and blue shark. Like the great white shark and others, these are very unique and important members of a healthy marine ecosystem. Without them, both the oceans and mankind are the lesser for it.

Teeth & Tuna: ICCAT and EU consider tuna and shark limits

In past postings I have mentioned the International Commission for Conservation of Atlantic Tuna (ICCAT). It is the primary organization responsible for setting regulations regarding the taking of Bluefin Tuna in the Atlantic. That population is very close to reaching the classic "tipping point", where declining populations will suddenly plummet as the biological reproductive infrastructure collapses due to over-fishing. Already the population figures are showing staggering declines.

On a positive note, the ICCAT is meeting in Morocco and many of the participants, including representatives from the European Union and the United States, are feeling the heat from conservation organizations armed with not just "tree hugger" rhetoric but solid scientific data. There are several proposals on the table - from reduced catches to complete moratoriums, particularly in Atlanctic breeding grounds. (Read Oceana press release.)

Oceana also has announced that the European Union is seriously considering several regulations regarding the commercial taking of several pelagic shark species, all of which having been adversely impacted either as bycatch from longline fishing for tuna or by being specifically sought after. Included for discussion are thresher, hammerhead, mako, and blue sharks. (Read Oceana press release.)

“The EU plays an important role in shark fisheries in the Atlantic, and I’m glad to see them take this strong and positive stance to lead sustainable fishing for these species. If the rest of the ICCAT parties follow this lead, we will make a huge advancement in securing the future of these vulnerable animals,” declared Ricardo Aguilar, Director of Research for Oceana in Europe.

Since I have started this blog, I have watched Oceana.org grow as an international marine conservation organization with a particularly proactive stance: a growing force to be reckoned with. Let's wish them continued success.