The Megamouth Shark Specialist: Dr. Jose Castro Discusses his Rare Expertise

Dr Jose Castro

Megamlouth shark specimen being studied

Megamouth Shatk internal structure

Megamouth sharks are one of the most elusive shark species in the world. Since their discovery in 1976, megamouths have been documented between 50 and 60 times; yet only a handful of specimens are on diplay at aquariums. Exceeded in size only by whale sharks and basking sharks, the large megamouth shark uses its wide jaws to filter for plankton in the deep-sea. Recently, biologist Dr. Jose Castro of NOAA Fisheries had a unique opportunity to help dissect a rare megamouth shark on display at the Okinawa Churaumi Aquarium in Japan.

They don’t call Castro a specialist for nothing. In 1994 he was part of the first ever female megamouth shark dissection at Fukuokka, Japan, and has dissected the only specimen caught in the Atlantic. We met with Castro to ask about the recent dissection and to learn more about the elusive megamouth.

How did you first get involved with megamouth shark research and dissections?

In 1994, a female megamouth was stranded in Fukuokka, Japan, and I was invited by Senzo Uchida of the Okinawa Churaumi Aquarium, to help with the dissection. Everyone was particularly excited that the shark was a female because we had the opportunity to investigate reproduction questions. For years that was the only dissection of a megamouth, and to this day the majority of information known about the species comes from that one shark. Later, the Brazilians invited me to document a megamouth caught off the coast of Brazil. Of course there are more megamouths in the Atlantic, but just one confirmed specimen has been found there.

What is it like dissecting a megamouth shark?

I dissect big animals all the time. But when I was working in Japan with the dissection team led by Dr. Keiichi Sato, it was a different and fantastic experience. We were not just examining the megamouth, we were preparing an exhibit for the aquarium. On one side of the creature we removed the muscle to expose the organs and skeleton, which was made of cartilage and connective issue. Visitors could actually see the animal’s anatomy. The dissection was a difficult and time-consuming process, and it didn’t help that the animal was preserved before we started, so the smell was horrible.

What do you hope people will learn from the megamouth display at the Okinawa Churami Aquarium?

The Okinawa Aquarium is one of the greatest in the world. The previous director, Senzo Uchida, was the first person to successfully keep whale sharks and manta rays in captivity. The research and curiosity behind the scenes give the public a chance to see what these creatures are really like. The megamouth specimen will be a part of a very unique filter-feeder exhibit along with the head of a 27-foot basking shark. I hope this will spark interest in the visitors the way it has for the scientists.

How does your work make a difference in shark management?

We have done a good job managing shark fisheries in this country, but not on an international scale. Sharks are among the last group of large vertebrates being destroyed by humans, and it has taken us a long time to realize we need new methods. Shark finning and other practices threaten the future of sharks, and we need international cooperation to make a difference. Luckily, the pursuit of science bridges countries and connects people to our oceans.

What is the one thing you want the public to know about megamouth sharks?

We hardly know anything about this shark. Through tagging we know that it goes up and down in different depths at night, but tags cannot tell us the bigger picture of what the shark is doing and why. The most we have learned about these creatures is through necropsies, or looking at them after they’ve died. We have yet to discover everything about these mystifying creatures: their behavior, reproduction, physiology, and some anatomical features. The first one was discovered in 1976, but didn’t become known outside the science community until 1983. I think the megamouth shark shows how little we know about the oceans. A lot remains to be discovered, even about these large animals.

Permit are fun to catch

Permit is a species on the bucket-list of many anglers world-wide. Here’s a review of the fishery in Florida, where they’re found both on the flats and over deep water reefs.

Permit is a highly sought-after fish in Florida. Learn about the current and historical status of this fishery.

Permit (Trachinotus falcatus) have long been sought after by commercial and recreational fishers on Florida’s Atlantic and Gulf coasts. Though this species is a prized catch, little is known about the status of the permit fishery. Commercial landings are relatively low; however, recreational landings data are scarce and there is still much to learn about the permit’s basic biology. That’s why Fish and Wildlife Research Institute (FWRI) biologists, in collaboration with Bonefish and Tarpon Trust and Costa Del Mar, are conducting a multi-year study on permit biology, life history and movement patterns.

The study relies on anglers tagging and fin-clipping, which is collecting a tissue sample, permit they catch and release. Biologists can then track movement patterns (e.g., reefs to shore, reef to reef, inshore to offshore, south to north) when anglers recapture and report catches of tagged permit. In addition, FWRI scientists are conducting genetic analysis of fin clips to assess permit population structure and determine whether permit throughout Florida’s coastal and inshore waters share a single genetic stock. This valuable data can help Florida’s fishery managers determine the best management methods for permit. To learn more about how anglers can contribute to this research, read the article Tag a Permit for Research Gains.

This permit is fitted with a tag that will allow researchers to track when and where the fish is caught again if it is recaptured in the future.

History of the Fishery

Commercial landings accounted for the majority of the statewide permit landings before the net limitation amendment (Amendment Three to the Florida Constitution) went into effect July 1, 1995, making use of entangling nets (e.g., gill nets, trammel nets) illegal. Since then, the majority of permit has been taken by the recreational sector, which accounted for 82 percent of permit landings from 2001 to 2007 on average.

Commercial landings have been declining since 1998, which can be partially attributed to changes in commercial regulations. Fishers target permit in the 1.5- to 3-pound range, which is characteristic of permit of legal harvest size. Most commercial fishers along the Gulf Coast (where most of the landings come from) land less than 500 pounds of permit annually. This equates to approximately 250 fish or less, which is a relatively small number of fish compared to other commercial fisheries. In fact, the monthly average weight of permit landed per trip from 2006 to 2010 was less than 55 pounds for all months but August, when it was 75 pounds.

In 2011, the FWC eliminated all directed commercial harvest of permit in state and federal waters off Florida. Since then, only 100 permit may be kept as bycatch by commercial fishers who hold a saltwater products license and a restricted species license and who are legally fishing for other species with gill or entangling nets in federal waters outside a Special Permit Zone, so landings remain low. The Special Permit Zone, an area in south Florida that includes all state and federal waters south of Cape Florida and south of Cape Sable, was created by the FWC in 2011 to provide additional protection to the species. There is no direct or indirect commercial harvest of permit inside the Special Permit Zone.

The recreational fishing sector accounts for the majority of statewide permit landings and most are taken along the Gulf Coast. However, recreational permit landings have increased along the Atlantic coast since 1997. The most productive months for recreational permit fishing appear to be March through June with a peak in April, based on estimates using Marine Recreational Fisheries Statistics Survey data (1982-2009). This coincides with the start of permit spawning season. There is a secondary peak in catches from November through January when permit aggregate at warm-water areas such as around power plants, allowing recreational anglers to more easily find them.

Permit are targeted by some anglers for catch-and-release sport fishing, but they are also commonly harvested and eaten. Data from 2004 to 2007 show anglers harvested an average of 59 percent of the recreationally caught permit. Since permit form large schools that will gather by reefs and wrecks for days at a time, they can be easily targeted by spear-fishers and hook-and-line anglers once the schools are located, especially during spawning season. In 2011, the FWC implemented regulations to protect adult permit aggregations found along Florida’s wrecks and reefs from too much fishing pressure. Managers also changed size and bag limits and established a closed harvest from May through July inside the Special Permit Zone. The closed season equates to catch-and-release fishing only during spawning. Both of these changes help to protect both juvenile and adult permit.

For a map of the Special Permit Zone, visit the Permit, Florida pompano and African pompano regulations page. For up-to-date permit fishing regulations, always check the FWC Saltwater Fishing Regulations.