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Background: In the 1950s, the state of Hawaii introduced blue-lined snappers (taape) from the Marquesas into waters around Oahu. The rationale for this was that snappers were rare in Hawaii, and these would provide a desirable game fish for sport fisheries. Since then, the taape has successfully established itself on all major Hawaiian islands and as far northwest as the island of Midway. In fact, if you go diving in waters around Oahu and other main islands, it is not uncommon to see large schools of taape mingling closely with certain species of native fish such as goatfish. Unfortunately, the taape has not proven quite as popular for fishermen as expected. In fact, many fishermen suspect that taape, through predation or competition for resources, are in part responsible for the decline of more desirable species of reef fish. |
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Introduced fish: In collaboration with Hawaii Institute of Marine Biology, we have been conducting necropsy surveys of taape (photo) near sewer outfalls around Oahu since 2002. The purpose of this was check for liver tumors as part of a statewide monitoring effort mandated by the Environmental Protection Agency. During these surveys,, we found that a high percentage of taape (40-60%) have infections with protozoa (lower left) and bacteria (lower middle) in the spleen and kidney along with miscellaneous parasites such as these worms in muscle (red arrow lower right). This finding posed two concerns. First, because taape were introduced, there is the possibility that these microbes were introduced along with taape from the Marquesas to Hawaii. Similar microbes that have been introduced into terrestrial ecosystems in Hawaii from the mainland have had significant impact on populations of terrestrial native fauna. Given this precedent, there was the concern that pathogens from taape could be transmitted to native fish. In 2003, the Hawaii Coral Reef Initiative provided funding to look into this very issue. The result was a launching of a collaborative study between USGS Cooperative Fisheries Studies Unit, Hawaii Department of Aquatic Resources, Oregon State University and the Hawaii Field Station. |
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Goatfish and taape share parasites: We looked at 4 different species of goatfish including the multiband (Parupeneus multifasciatus), the yellowstripe (Mulloidycthies flavolineatus), the yellow tail (M. vanicolensis) and the orange band (M. pflugeri). We found a variety of microbes, and the type of microbe depended on the type of fish affected. For example, for protozoal infections in the spleen, over 80% of plugers goatfish were infected followed by 50% for yellowstripe, 30% for yellow tail, and less than 1% for multiband. Given the high prevalence of infection with protozoa for orangeband goatfish, the question naturally arises whether taape are getting the parasite from goatfish or vice versa. Two ways to answer the question exist. We can try to examine museum specimens of this species collected before taape were introduced into Hawaii (1950s) or we can try and get taape from the Marquesas and see if they are infected with this parasite. If that is the case, the likelihood the parasite was introduced into Hawaii would be higher.
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Tumors in fish: We have also been looking into the potential causes of tumors in butterfly fish. On Maui and Lanai, ca. 5-10% of butterfly fish are affected with pigment cell tumors (as pictured at left in milletseed butterfly fish). Since earlier studies done in the 1980s, the percent of butterfly fish affected by these tumors has decreased, however, so has the numbers of fish, so it is hard to determine which came first. Potential future investigations include trying to determine if these tumors are transmissible and if so, what kind of virus could be responsible. |
