The information presented here represents preliminary research as the result of ten-weeks of investigation in-residence at the National Museum of Natural History. This is not an official publication of the information.

As preliminary information, results and/or findings should not be cited as part of conclusive work. Please contact the authors first if you wish to utilize the information presented here.

Abstract

To test the hypothesis that the marine fish fauna of Trinidad is the same as that of Tobago, 494 lots of specimens from Trinidad and Tobago, housed in the Fish Collection of the Smithsonian Institution's National Museum of Natural History (NMNH), were examined for capture locations and to verify species identification.

Additional data from four research cruises done by the R/V Dr. Fridtjof Nansen around Trinidad and Tobago in 1988 supplemented the collection-based data. These data supported spatial analyses of occurrence by species, families and higher taxa around both islands.

The findings indicate significant differences in the fish species composition around both islands thus rejecting the null hypothesis; however, no conclusive statements can be made due to unequal attempts to document the marine fishes of both islands in terms of sampling methods and intensity.

Tobago has been subjected to serious systematic inventory, most recently through the efforts of Dave Hardy and NMNH personnel, resulting in over 1300 lots of Tobago specimens compared to 200 for Trinidad in the NMNH Fish Collection.

Trinidad has neither been subjected to similar rigorous research nor have the specimens been collected via similar, comparable sampling techniques. Despite this caveat, these results have implications for marine resource management, in terms of necessitating different strategies based on the dominant groups around each island, and provide direction for future research.

This research suggests that the marine fish fauna of Trinidad is not the same as that of Tobago.

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Introduction

The twin-island state of Trinidad and Tobago lies at approximately 11° N and 61° W just north of Venezuela. While it is largely accepted that Trinidad resides completely on the south American continental shelf, Tobago's origins remain in question.

For example, a 1989 report from the Institute of Marine Research in Bergen, Norway states "Tobago in its entirety [lies] on the continental shelf [of south America]." Recently however, Itturalde-Vinent and MacPhee (1999) indicated that Tobago lies on the Caribbean plate and originated further west than its present position, while Trinidad resides on the South American plate.

Despite the continuing debate about Tobago's origins, no doubt exists about the difference in the marine environments around both islands. Trinidad closely resembles South America while Tobago displays more oceanic characteristics.

Considerable research exists on the marine fish fauna of both Trinidad and Tobago (Ramjohn 1999); however, no attempt has ever been made to analyze the marine fish fauna of the two islands separately.

Map of Trinidad and Tobago showing their position relative to each other and to Venezuela, and the politically determined T&T/Venezuela delimitation line. Tobago lies approximately 23 miles northeast of Trinidad (36 km or 20 nautical miles). The 11° N line of Latitude, adopted in this project as the point of separation between both islands, is highlighted in red. Source: Fisheries Division, Ministry of Agriculture, Land and Marine Resources, Trinidad and Tobago, W.I.

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Methods

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Results

 

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Discussion

This research highlighted several problems associated with attempting analyses of this nature. Unequal sampling efforts for Tobago, in terms of intensity and sampling methods, resulted in artefacts in the data, e. g., cryptic reef species such as the Gobiidae are well represented in Tobago but not in Trinidad. However, Trinidad's reefs have never been inventoried, thus this evidence is inconclusive. Alternatively, the absence of Siluriform species in Tobago may not reflect bias in sampling, but rather be a result of habitat selection. The inclusion of station data from the R/V Dr. Fridtjof Nansen provided additional species and location data that was comparable across both islands, thus lessening the effects of sampling bias.

Problems inherent in computerized data also became apparent, for example, examination of some specimens and accession records that were computerized as from Trinidad and Tobago proved them to be from Ilha da Trinidade off the coast of Brazil. Species with very similar names also prove difficult to deal with based on only catalog data, e.g., Steindachnerina argentea (Gill 1858) vs. Steindachneria argentea Goode & Bean 1896, both of which occur in the area; the former is a freshwater species of Curimatidae and the latter a marine species of Merlucciidae.

This project reinforced the idea that voucher specimens are vitally important for natural history research. Misunderstandings and erroneous reports can be clarified by reference to archived material such as those available in the National Museum of Natural History. The addition of datasets from other museums such as: the American Museum of Natural History, with 221 records; the Academy of Natural Sciences Philadelphia, with 670 records; and the Royal Ontario Museum, with 650 records (Ramjohn 1999), will improve this analysis. Further research will determine whether zoogeography or ecology is responsible for observed differences between the islands.

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Conclusions

This preliminary zoogeographic analysis of marine fishes around Trinidad and Tobago, despite the inherent biases in the available data, rejects the null hypothesis that the marine fish fauna of Trinidad is the same as that of Tobago. The limitations of the data, however, do not allow the adoption of the alternative hypothesis that the marine fish fauna between the two islands is different.

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Literature Cited

Iturralde-Vinent, Manuel A. and R. D. E. MacPhee. 1999. Paleogeography of the Caribbean Region: Implications for Cenozoic Biogeography. Bull. Am. Mus. Nat. Hist. No 238. New York.

Institute of Marine Research. 1989. Surveys of the Fish Resources in the Shelf Areas Between Suriname and Colombia, 1988. Bergen, Norway.

Ramjohn, David D. 1999. Checklist of Coastal and Marine Fishes of Trinidad and Tobago. Marine Fishery Analysis Unit, Fisheries Division, Ministry of Agriculture, Land and Marine Resources, Trinidad and Tobago. Fisheries Information Series No. 8, 151 p.

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Acknowledgements

Dr. Bruce B. Collette - for his superb guidance and faith in my ability

Mr. J. David Hardy - for allowing me to ride his coat-tails

Drs. G. D. Johnson, Jeff Williams, Carole Baldwin, Tom Munroe and Susan Jewett - for putting up with me

Mary Sangrey - for her tireless efforts to make this program a success

Nina Butler - for keeping the funds flowing

Jerry Kinan - for making sure I didn't get lost at MSC

Dr. Edward Murdy - for the unpublished keys to the Eleotrids and Gobiids

Drs. George Sedberry and Jack McGovern - for their support of my participation in this program

Megan Beck - just for the heck of it

my fellow RTPers - for the friendships and memories

And last but not least, Bill and Jean Lane - for the funding that made this possible.

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ENTOMOLOGY

Sarah Garrett
"An Inventory of Leafroller Species of Moths of the Great Smoky Mountains National Park"

Abstract / Summary

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