Shark tours have become increasingly popular in Hawaiian waters, but tour operators that feed shark to assure their presence are now facing opposition from several different directions.

Sharks are an integral part of Hawaiian folklore and some Native Hawaiians consider sharks to be ancestral gods, aumakua, who helps fishermen by chasing fish into nets and guiding canoes safely back to shore. Tour boats feeding sharks for entertainment is therefore viewed as disrespectful by many.

“The disrespect of the aumakua, that’s what hurts us the most,” said Leighton Tseu, a Native Hawaiian who considers sharks ancestral gods.

Surfers and swimmers are on the other hand more worried about the potential hazards of teaching sharks to associate people with food. There are also fears that shark feeding will attract larger numbers of sharks to these waters and that the practise of feeding them will lure them closer to shore than before.

A third concern has been raised by environmentalists – how does daily shark feedings affects the ecological balance of Hawaiian waters? George Burgess, shark researcher at the University of Florida, says shark populations are likely to increase in areas where tours feed sharks daily, and that an inflated shark population might consume more prey, depleting other marine life. Burgess also fears that the feedings may attract so many sharks to those spots that sharks become scarce in other regions. This is naturally a large problem, since sharks are apex predators necessary for the overall balance of the ecosystems in which they exist.

Carl Meyer of the Hawaii Institute of Marine Biology does not share Burgess’s concerns, at least not for Hawaiian waters. Research carried out by Meyer shows that a majority of the sharks found at Haleiwa, a popular tour site, are Galapagos and Sandbar sharks – two types of sharks rarely documented attacking humans. Most of Hawaii shark attacks are carried out by Tiger sharks, and these sharks only account for 2 percent of the tour site’s sharks. Meyer’s research also shows that sharks at the North Shore tour site have not made any changes to their seasonal breeding and migration cycles since the feedings started.

Legal matters
Feeding sharks in Hawaiian waters is prohibited by state law, while federal law – which governs waters between 3 miles to 200 miles from the coast – prohibits the feeding of sharks off Hawaii and Pacific island territories like American Samoa. Fishermen are however allowed to bait sharks, and scientists engaging in government-funded research are also exempt from the ban.

The National Marine Fisheries Service in Honolulu is currently investigating Hawaiian tour operators offering shark safaris.

Genetic pattern analysis strongly suggests that California and British Columbia urchins are not connected via larval dispersal and comprise two distinct populations. Sea urchins have one of the longest larval periods of any known marine invertebrate and it has therefore been tempting to assume that ocean currents must be mixing urchin larvae all over the place, making it difficult for any distinct populations to form. But research results from the University of California now indicate that these two Pacific populations are two clearly separated ones.

Sea urchins –  Picture from the Red Sea

Together with former* graduate student Celeste Benham, marine biology professor Ron Burton of the University of California at San Diego have analyzed 500 adult sea urchins from Californian waters across five microsatellite markers and then compared the genetic patterns to an existing, similar database of 1,400 urchins from British Columbia. The Californian specimens were collected off the coast of San Diego, Los Angeles and Mendocino counties.

The genetic signatures found by Burton and Benham strongly suggest that the southern and northern populations are not connected via larval dispersal.

“From my evolutionary perspective, our results are important because they imply that, even on long time scales, there is no mixing, Burton explains. This means there is at least the potential for populations to adapt to different ocean conditions and gradually diverge. This is the first step in the two populations potentially becoming different species.”

This is the first time scientists have detected any population structure in the species. Similar studies carried out in the past have used fewer genetic markers and found no population genetics structure in the species despite having tested many different patches across its range.

“The take-home message of this study is that if you use more markers and newer techniques you will find some population differentiation that before nobody found,” says Burton.

* Benham is now a research assistant at the marine mammal laboratory at Hubbs-SeaWorld Research Institute in San Diego.

Purse seine fishing regionally banned by the United States Western Pacific Regional Fishery Management Council

According to a report from the Australian Broadcasting Corporation, the United States Western Pacific Regional Fishery Management Council has decided to ban so called purse seine fishing in parts of the Western Pacific. The council is concerned about the large boats with massive nets that use the purse seine fishing technique in the Western Pacific and fear that they might deplete the local fish populations, especially when it comes to the popular foodfishes yellowfin tuna and skipjack tuna. The ban concerns all federal waters off Guam, the Northern Marianas and American Samoa and in this area all purse seine fishing will be illegal within 75 nautical miles of the shore.

You can fin more information here

The Yellowfin tuna is a popular food fish and is known to reach a length of 239 meters (94 inches). It lives in the upper 100 meters (330 feet) of the ocean and is found in both tropical and subtropical parts of the world. The severe depletion of the Bluefin tune has become a problem for the Yellowfin tuna, since consumers have begun to purchase Yellowfin tuna as a replacement for Bluefin tuna.

The Skipjack tuna is smaller than the yellowfin and can only reach a length of roughly 100 cm (3.3 feet). It is a popular foodfish world wide, but especially sought after in Japan where it is used to make traditional katsuobushi, which is an important ingredients in dashi (a type of fish stock).