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MarineBio Newsletter 2


MarineBio News

MarineBio is pleased to announce our 2nd Newsletter! We welcome your feedback on the content of the newsletter and would love to hear what you're interested in reading! Send your comments to:

MarineBio is pleased to announce some new additions to the site.

Featured Species: The Atlantic Bluefin Tuna

Atlantic bluefin tuna, Thunnus thynnusOne of the most highly evolved fish in danger of overfishing is the Atlantic bluefin tuna, Thunnus thynnus. These are some of the most magnificent creatures in the sea, and one of the most prized by the fishing industry. One fish can sell for tens of thousands of dollars. The highest amount paid for a bluefin was $180,000 on the Japanese fish market.

The Atlantic bluefin tuna is the largest member of the Scombridae family (albacores, bonitos, mackerels, tunas). It is also one of the largest bony fishes and can reach up to 10 feet in length and weigh up to 1,500 pounds, although these are rare. They can dive as deep as 3,000 feet, and are known to swim long distances as they are a highly migratory species. According to tagging research, they swim from the US Atlantic coast to feeding grounds in the Mediterranean. Spawning grounds of the Atlantic bluefin have been found in the Gulf of Mexico. Swim speeds reach up to 35 miles per hour.

Description: Atlantic bluefins are dark blue to black near the dorsal surface and silvery near the ventral surface. The Altlantic bluefin is known for the finlets that run down the dorsal and ventrals sides toward the anal fin. There are 12 to 14 spines in the first dorsal fin and 13 to 15 rays in the second dorsal fin. The anal fin has 11 to 15 rays.

Even though bluefin tuna can reach lengths of up to 10 feet, they are more commonly found from 1.5 to 6.5 feet in length. Adult weights range from 300 to 1,500 pounds. The average lifespan is 15 to 30 years.

Atlantic bluefin are homeothermic ("warm-blooded") and therefore able to thermoregulate keeping their body temperatures higher than the surrounding water, which is why they are so well adapted to colder waters.

World Range and Habitat: Atlantic bluefin live in subtropical and temperate waters of the North Atlantic Ocean, the Mediterranean, and Black Seas. They are highly migratory and widely distributed throughout the Atlantic and can be found from Newfoundland all the way to the coast of Brazil. They range in the eastern Atlantic as far north as Norway and down to northern West Africa. Atlantic bluefin spawn in the Gulf of Mexico between April and June and in the Mediterranean Sea in June and July. Bluefin tagged in the Bahamas have been captured in Norway as well as off the coast of Brazil. Bluefin in the South Atlantic belong to a distinct southern population, with known spawning areas south of Java, Indonesia. The bluefin is a pelagic, schooling fish tending to group together according to size.

Feed Behavior: Atlantic bluefin tunas consume smaller fishes such as flying fish, herring, whiting, and mullet as well as squid, eels, and crustaceans.

Reproduction: Although Atlantic bluefins are widely distributed and migrate thousands of kilometers, there are two confirmed spawning locations—the Gulf of Mexico in the western Atlantic and the Mediterranean Sea in the eastern Atlantic. Although many ecological and environmental variables undoubtedly affect both the location and productivity of spawning in these two areas, relatively little is known concerning why bluefin spawn where they do.

Spawning in the Gulf of Mexico occurs between mid-April and mid-June when females, which mature around age 8, release approximately 30,000,000 eggs each. The highest density of bluefin larvae, the primary indicator of spawning, occurs in the northern Gulf of Mexico with lesser larval concentrations appearing off the Texas coast and in the Straits of Florida.

In the eastern Atlantic, spawning occurs exclusively in the Mediterranean and Adriatic Seas from June through August, with the highest larvae concentrations appearing around southern Italy. Although some fishery biologists believe that eastern Atlantic bluefin reach sexual maturity several years earlier than western Atlantic bluefin (possibly as young as ages 4 or 5), this understanding has been criticized.

Warnings & Comments: Threatened, IUCN Red List
International sport fishing for giant bluefin originated about 100 years ago, becoming popular domestically in the early 1900s. The Sharp Cup in Nova Scotia was a distinguished international bluefin tournament held from the early 1930s through the 1960s, with a peak landing of 1,760 fish in 1949. Many other tournaments existed throughout the NE United States until the mid-1960s, when giant bluefin abundance near tournament sites appeared to decline. Although studies have been inconclusive regarding these changes, hypothesized causes include changes in water temperature, oceanic currents. abundance of feed, and a declining population of giant western Atlantic bluefin.

Prior to 1970, sport fishing was exclusively recreational, as giant bluefin tuna had a commercial value of only $.05 per pound. Giant trophy tuna that were not kept for personal display or consumption were sold to cat and dog food producers. With the development of the Japanese specialty market in the early 1970s, giant bluefin tuna suddenly represented big money to traditional sport fishermen. Perspectives on the fishery shifted, and the recreational character of the fishery was altered by economic opportunity. A giant 225-kilogram trophy fish was, by the late 1970s, a highly valued Japanese delicacy. Participation exploded and the giant bluefin fishery capitalized quickly.

Now many "recreational anglers" also obtain commercial permits, so that virtually all giant bluefin tuna currently caught are marketed commercially, except for a small scale catch-and-release sport fishery in the Bahamas. A substantial charter- or party-boat fishery for small bluefin tuna also exists from North Carolina to Massachusetts. Estimated at more than 15,000 recreational anglers annually, this is the only U.S. fishery allowed to catch bluefin smaller than the minimum commercial size (70 inches from the tip of a fish's snout to the fork of its tail)....

Click here to visit MarineBio's Atlantic bluefin tuna page

Issues in Marine Conservation – Overfishing

Atlantic Bluefin Tuna
Atlantic Bluefin Tuna - a species in danger of overfishing

"Answers to ocean recovery lie in fishing at a pace slower than fish can breed, farming seafood less destructively and giving consumers information to vote their conscience with their wallet. So, yes, there is hope." – Dr. Carl Safina

The supply of fish as protein to the world’s populations is a huge industry that millions of people depend on for their livelihood. Many of these people and millions of others also depend on the fishing industry for food. Almost 100 million tons of fish are "harvested" annually. Until recently, fishing appeared to be a bottomless source of revenue and food. Today, FAO estimates that more than 70% of the world’s major fish stocks have been dangerously exploited, 9-10% of which have been fully depleted or are recovering from depletion. The bottom line is that these fish stocks are being fished at a rate that is not sustainable.

Overfishing is a problem that has a domino effect. In addition to endangering a wide variety of fish species, overfishing can also harm the oceans’ ecosystems by disrupting food webs. For example, Steller sea lion populations in Alaska began declining as their food sources such as cod, pollock, and mackerel were depleted. Another example is that decreases in populations of herbivorous fish that live on the plant algae covering coral reefs causes damage to the reefs as algae overgrows and blocks the sunlight needed for coral growth.

The techniques and equipment used by the fishing industry are not only contributing to overfishing of the very stocks they depend on, but also declines in populations of other non-targeted species that get caught in non-selective gear such as drift nets, purse seine nets, long lines, or trawlers as “bycatch.” Trawlers can also damage ecosystems as they’re dragged across delicate coral reefs or the bottom of the seabed destroying other habitats.

The key to stopping this disturbing trend is to combine scientific knowledge on fish populations and their biology with fisheries management today. As Dr. Carl Safina stated in the quote above, the simple solution is that fish need to be harvested at a rate slower than they can reproduce. The alternative is that we simply keep running out of species to fish for, and the fishing industry destroys itself as well as the oceans that supported it.

You can help by being selective as to what kinds of fish you consume. A decrease in consumer demand for certain species will influence the fishing industry to look for alternatives and find species that can be fished sustainably. To find out more, please visit the Blue Ocean Institute’s ocean-friendly seafood page and the Audubon's National Seafood Wallet Card. You can also find out what fish stocks are at the greatest risk worldwide at FAO’s State of the World’s Fisheries and Aquaculture site and in the US by visiting the National Ocean and Atmospheric Administration’s status of US fisheries. For additional detail on this problem, Greenpeace has an excellent Web site filled with information as well.

Current Research in Marine Biology: Preliminary Report of the US Commission on Ocean Policy

It’s official. The US Government has neglected the oceans for far too long. Says who? Believe it or not, the US Government in its "Preliminary Report of the US Commission on Ocean Policy". The US Commission on Ocean Policy ( was established in 2001 as a result of the Oceans Act of 2000 to:

"make recommendations for a coordinated and comprehensive national ocean policy that will promote:

  1. protection of life and property
  2. stewardship of ocean and coastal resources
  3. protection of marine environment and prevention of marine pollution
  4. enhancement of maritime commerce
  5. expansion of human knowledge of the marine environment
  6. investments in technologies to promote energy and food security
  7. close cooperation among government agencies
  8. U.S. leadership in ocean and coastal activities."

To make these recommendations, the Commission was instructed to investigate and consider a wide range of factors that impact the health of the ocean including existing policies, economic issues, inter-governmental organization and structure of agencies involved in ocean issues, and the science needed to improve ocean health. In addition to the Commission, a science advisory panel was established to help ensure the scientific accuracy of the Commission’s report.

The Commission was guided by a set of fundamental principles including:

Tropical paradise...

The Commission identified a number of threats to ocean health in the report, and made recommendations for actions to address them.

One of the primary recommendations resulting from the Commission’s preliminary report is the establishment of a National Ocean Council in the Executive Office of the President composed of cabinet secretaries and agency directors with ocean-related responsibilities. In addition, a Presidential Council of Advisors on Ocean Policy will be established consisting of nonfederal representatives from state, territorial, tribal, local governmental and nongovernmental agencies, and academic institutions.

The Commission also recommended that national ocean policy be supported by quality ocean education at all levels and across all disciplines, and that ocean-related federal agencies take responsibility for outreach and education of the public as part of their mission.

Internal collaboration among federal agencies responsible for coastal management was recommended in the report as a way to maintain economic growth, but with greater capacity to guide growth in a way that will not damage sensitive coastal ecosystems.

The growing number of new offshore interests such as aquaculture and wind energy development added to existing marine commerce industries including fisheries and oil and gas may create a greater environmental burden on offshore waters as well as conflict. The Commission recommends a coordinated offshore management regime to safeguard against damage to offshore resources.

The Commission also addressed the growing problem of ocean pollution caused by a wide range of contaminants and recommended that measurable ocean pollution reduction goals be established, and that coordination and cooperation among agencies, programs, and individuals is essential to implementing effective management tools for these issues.

Fishery management is one of the largest problems facing our oceans because of depletion of fish stocks driving many species to near extinction and degradation of natural habitats caused by fishing equipment. The Commission recommends as part of a long-term plan that a scientific approach be used so that fisheries can be managed based on maintaining health to the ecosystems, and therefore health to the fisheries. The Commission also recommended that the US accede to the United Nations Convention on the Law of the Sea in order to protect national interests and cooperate with the global community on ocean conservation.

Finally, to fund implementation of these recommendations, the Commission recommended establishing an Ocean Policy Trust Fund with revenue collected from offshore oil and gas and other offshore interests. encourages you to read the preliminary report published by the Commission which is available online in html and pdf formats. Provided there is follow-up to the action items recommended in the report, there is hope that the health of our oceans will no longer be neglected. Feedback and support of the Commission and its report by US citizens is needed in order to keep ocean conservation high on the agenda of the US government. The next step will be to address the issues involving enforcement which is often the greatest challenge.

MarineBio Recommends

Song for the Blue Ocean Encounters Along the World’s Coasts and Beneath the Sea written by Dr. Carl Safina. This book is a moving account of Dr. Safina’s travels and quest for truth about the state of the world’s oceans. Dr. Safina is a world-renown scientist and fisherman who has made it his mission to educate people about the damage overfishing is causing and the need for sustainable fisheries management and sustainable seafood choices through his non-profit organization the Blue Ocean Institute. Song for the Blue Ocean tells the story from both perspectives – the oceans’ and the fishermens’ in a way that defines the grim reality of the state of our seas yet also leaves room for hope in an increasingly hopeless situation. The book is unique in that it is beautifully written, and comes across as part science, part travel narrative, and part treatise on ocean conservation. MarineBio gives this book 5 starfish, and we encourage anyone interested in the ocean to read it.

The Blue Planet – Seas of Life – These documentaries contain astonishing footage of the oceans and their creatures from all regions of the world and from all levels of the sea from the coasts to the deep. Many of you request recommendations for videos on marine biology – well, these are the most beautifully photographed and informative videos that we know of. Each of the 8 documentaries covers a different region, and the sea life documented on film varies in size from microscopic plankton to the enormous blue whale.

Advice for Up & Coming Marine Scientists

Cuttlefishes!One of the most common questions received by MarineBio from members interested in a career in marine biology is what schools offer post-high school education in marine biology and which ones are best?

We encourage all of you with questions like these to check out our Education Resources page.

We plan to feature specific academic institutions and the curricula they offer in future issues of the MarineBio Newsletter.

A great education resource is the NOAA's Ocean Explorer cd rom. This cd provides the entire site's content through January 2003 so that you can explore the site offline. To obtain a free copy of the cd visit: NOAA Ocean Explorer: Education - CD-ROM.

The Sea Below ~ Expedition :: Bonaire

Stay tuned for the next issue of the newsletter for details and photos from MarineBio’s Expedition to the island of Bonaire!

Lighthouse Point, Bonaire

We hope you found this month's Newsletter interesting. Click around for more species, more research and more Marine Biology News. As always, we welcome all feedback.

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