Introduction

This report contains the first comprehensive documentation of the marine fish fauna of Kimbe Bay, New Britain. It is based primarily on a field survey conducted during the Nature Conservancy's Rapid Ecological Assessment (REA) of Kimbe Bay during December, 1994. The principle aim of our survey was to provide a comprehensive inventory of the reef and shore fishes of Kimbe Bay. The results facilitate a comparison of the faunal richness of Kimbe Bay with other parts of Papua New Guinea and adjoining regions in the Indo-Australian Archipelago. We emphasise that the list of fishes presented below is still incomplete. However, the results of the present survey coupled with a basic knowledge of the cryptic component of the fauna in other areas allow us to provide what we believe is an accurate estimate of Kimbe Bay's overall fauna.

Methods

This checklist is a compilation of data collected during the Nature Conservancy's REA survey of Kimbe Bay in 1994 and data collected during numerous field trips to the area by both authors. During the REA survey, each of us recorded data at 35 different sites in Kimbe Bay. Therefore, data were accumulated for a total of 70 sites. Our basic method consisted of underwater observations utilising SCUBA equipment. A single, 45-60 minute, dive was made at each site. The name of each species encountered was written on plastic sheets attached to a clipboard. An average of 138 species was recorded at each site. The majority of sites consisted of steep-sided pinnacle reefs. Our technique routinely involved a rapid descent to 30-35 metres, spending 5-10 minutes there, and then a slow, zigzag pattern was traversed on the ascent. The majority of time was spent in the 2-12 meter depth zone, which consistently harbours the largest number of species. At each site we endeavoured to include a representative sample of all bottom types and habitat situations, for example reef top, steep drop-offs, caves (utilising a flashlight if necessary), rubble and sand patches, etc.

In addition to the REA survey, we have both visited the Kimbe Bay area on numerous occasions and have recorded additional species during these visits. All species recorded from Kimbe Bay during the REA and during subsequent visits are included in the check list. Only the names of fishes whose identification we were absolutely sure of were recorded. However, there were very few, less than about two percent of those observed, that could not be identified to species level. Between us, we have accumulated more than 30 years experience working on the reef fishes of New Guinea and surrounding regions. This experience was a vital ingredient in the successful outcome of this survey.

Results

A total of 567 species were recorded during the REA survey and we have sighted or collected 265 additional species during other visits to the area. Therefore, the total known fauna of Kimbe Bay is 832 species belonging to 319 genera and 90 families. An annotated list of the fishes is included as part of this report. Nearly all of the fishes appearing in the list are illustrated in either Allen (1991 and 1993), Myers (1989), Kuiter (1992), or Randall et al (1990).

General faunal composition

The fish fauna of Kimbe Bay consists mainly of species associated with coral reefs. The most abundant families in terms of number of species are gobies (Gobiidae), damselfishes (Pomacentridae), wrasses (Labridae), groupers (Serranidae), cardinalfishes (Apogonidae), butterflyfishes (Chaetodontidae), surgeonfishes (Acanthuridae), blennies (Blenniidae), snappers (Lutjanidae), and parrotfishes (Scaridae). These 10 families collectively account for 61 percent of the total fauna (Fig. 1 and Table 1).

Table 1. Family rankings in terms of number of species for various localities in the Indo-Pacific region. Data for Flores is from Allen and Kuiter (unpublished), Christmas Island from Allen and Steene (1979), Marshall Islands from Randall and Randall (1987), and from Winterbottom et al (1989) for the Chagos Archipelago.

Family	Kimbe Bay	Flores, Indonesia	Christmas Island, I.O.	Marshall Islands	Chagos Archipel.
Gobiidae	1st	1st	3rd	1st	1st
Pomacentridae	2nd	3rd	2nd	4th	3rd
Labridae	3rd	2nd	1st	2rd	2nd
Serranidae	4th	5th	4th	3th	4th
Apogonidae	5th	4th	9th	8th	6th
Chaetodontidae	6th	7th	6th	8th	11th
Acanthuridae	7th	8th	7th	7th	8th
Blenniidae	8th	6th	8th	6th	9th
Lutjanidae	9th	9th	13th	18th	7th
Scaridae	10th	10th	12th	10th	12th

The relative abundance of Kimbe Bay fish families is similar to other reef areas in the Indo-Pacific, although the ranking of individual families is somewhat variable as shown in Table 1. The moray eel family Muraenidae is consistently among the most specious groups at other localities, and are no doubt numerous in Kimbe Bay. However, we did not detect many species due to their cryptic habits. They are best sampled with chemical icthyocides.

Behavioural modes and feeding relationships

The majority of Kimbe Bay fishes are diurnal coral reef species, which either live on or near the bottom, or forage on planktonic items a short distance above it (Figs. 2-3). Approximately 10 percent of the species are nocturnally active. One shortcoming of our survey techniques is that cryptic species are seldom sighted. These are fishes that live deep in the shadows of caves and ledges. They can only be sampled with the use of chemical ichthyocides. In some areas the cryptic component accounts for as much as 20 percent of the total fauna.

The association of consumers and consumed organisms, involving an incredibly diverse array of plants, invertebrates, and vertebrates, results in a complex, highly intertwined food-web. The overwhelming majority of Kimbe Bay fishes are either carnivores or planktivores, feeding on a wide range of invertebrates and fishes (Fig. 4). About 25 percent of the Kimbe Bay species are either herbivorous or omnivorous. Detailed information on the feeding habits of individual species is provided in the annotations in Appendix Table 1.

Zoogeographic affinities of the Kimbe Bay fish fauna

The fishes of Kimbe Bay belong to the overall faunal community of Indo-west Pacific fishes. The fauna is very similar to other areas within this vast region, stretching eastward from East Africa and the Red Sea to the islands of Micronesia and Polynesia. Although most families, and many genera and species are consistently present across the region, the species composition varies greatly according to locality.

Kimbe Bay, and New Guinea in general, are part of the Indo-Australian Archipelago, the richest faunal province on the globe, in terms of biodiversity. Species richness generally declines with increased distance from the Indonesian center of this region, although this effect is countered by a secondary region of speciation in the Red Sea-western Indian Ocean. The damselfish family Pomacentridae provides an excellent example of this phenomenon (Table 2). Approximately 138 species occur in Indonesia, 100 in New Guinea (87 at Kimbe Bay), and only 15 and 16 respectively at Hawaii and Pitcairn Island, which lie on the outermost fringe of the region.

Table 2. Number of Damselfish Species at Selected Localities.

Most of the species occurring in Kimbe Bay have relatively widespread distributions within the Indo-Pacific region. Nearly all coral reef fishes have a pelagic larval stage of variable duration, depending on the species. Therefore, the dispersal capabilities and length of larval life of a given species is usually reflected in the geographic distribution. The main zoogeographic categories for Kimbe Bay fishes are presented in Fig. 5. The largest segment of the fauna consists of species that are broadly distributed in the Indo-west and Central Pacific region from East Africa to the islands of Oceania. The remaining species have more restricted distributions within the Indo-Pacific region. In addition, 25 species have worldwide distributions, occurring in all tropical seas.

Discussion and recommendations

A total of 832 species are currently known from Kimbe Bay. A considerable number of mainly cryptic species have almost certainly remained undetected during our surveys. Therefore the overall fauna is estimated to consist of over 850 species. Although this total sounds impressive and is indicative of a very healthy ecosystem, it is not unusual for Papua New Guinea or adjacent waters. Investigations at Milne Bay and Madang by one of us (GRA) have revealed a similarly rich fauna.

Although the occurrence of Kimbe Bay endemics is highly unlikely, a number of fish species appeared to be far more common than in other parts of the Indo-Australian Archipelago. Included in this category are the cardinalfish Apogon neotenes, the butterflyfish Chaetodon ocellicaudus, the angelfish Pomacanthus navarchus, the parrotfish Chlorurus microrhinos, and the surgeonfishes Acanthurus fowleri and A. nubilus.

The configuration of the bay and its position relative to prevailing winds creates an unusually sheltered environment for the rich complex of seaward reefs. Coupled with the spectacular underwater terrain, composed largely of steep-sided, patch, saddle, or pinnacle reefs, it is one of the tropic's most exciting dive areas. Fishing pressure appears to be minimal throughout much of the bay and many of the reefs are simply too far away to be regularly visited by local fisherman.. The absence of large predatory fishes, such as groupers, was a feature of Kimbe Bay reefs. It is a common misconception that this phenomenon is indicative of over fishing. From our experience, Indo-Pacific reefs in general share this feature. Concentrations of large fishes are frequently highly localised and it is unusual to find many "hot spots" in an area the size of Kimbe Bay.

Although similar fish communities exist in other parts of Papua New Guinea, the habitat of Kimbe Bay is unique, as is the special "mix" or community of fishes found there. We therefore believe that Kimbe Bay is deserving of special conservation status in order to insure the long term protection of its ecosystem.

Summary

• The fish community of Kimbe Bay is estimated to be over 850 species of which 832 species have been observed or collected during our surveys.

• The fish fauna consists mainly of widely distributed Indo-Pacific species associated with coral reefs, but there is also a significant element found on sand/rubble bottoms.

• Gobies (Gobiidae) are the dominant group in Kimbe Bay in terms of number of species (98). Damselfishes (Pomacentridae) are also very diverse (87 species) and are perhaps the most abundant group in terms of number of individuals.

• The overwhelming majority of Kimbe Bay fishes (75%) are either carnivores or planktivores, feeding on a wide variety of invertebrates and fishes. The remaining 25 percent of the fauna is either herbivorous or omnivorous.

• There are probably no fishes that are unique to Kimbe Bay, but the overall community contains a unique "mix" of species. Several fishes that are rare in most other regions were common and vice versa.

• The abundance of steep-sided coral reefs, forming pinnacles, saddles, and patch reefs combine to form a highly unique environment, which is further enhanced by the relatively sheltered waters of Kimbe Bay.

• The combination of a rich and varied fish fauna, well developed coral reefs, and a spectacular, relatively pristine environment, is ample justification for the establishment of a special conservation status (marine park, reserve, etc.) for Kimbe Bay.

Acknowledgements

Max Benjamin of Walindi Plantation Resort and Walindi Diving has made a great personal and financial commitment to conservation of the marine ecosystems of New Britain. His support made this report possible. The Nature Conservancy financed and coordinated the Rapid Ecological Assessment in 1994, and through the efforts of Peter Thomas, they have continued to assist scientific projects in Kimbe Bay. Mahonia Na Dari Conservation and Research Centre has strongly supported our work. Fisheries Officers, Noah Taia and Joel Ade, and the University of PNG's Motupore Island Research Department have provided assistance and advice on numerous occasions. Thanks also to Dr. J. Randall, Dr. D. Hoese, Dr T. Gill, H. Larson and others for providing taxonomic advice on particular specimens.

References

Allen, G.R. 1991. Damselfishes of the world. Aquarium Systems, Mentor, Ohio.

Allen, G. R. 1993. Reef fishes of New Guinea. Christensen Research Institute, Madang, Papua New Guinea Publ. No.8.

Allen, G.R. and Steene, R.C. 1979. The fishes of Christmas Island, Indian Ocean. Australian National Parks and Wildlife Service, Spec. Publ. 2: 1-81.

Myers, R.F. 1989. Micronesian reef fishes. Coral Graphics, Guam.

Nelson, J.S. 1984. Fishes of the world. John Wiley and Sons, New York.

Kuiter, R. H. 1992. Tropical reef fishes of the Western Pacific - Indonesia and adjacent waters. Percetakan PT Gramedia Pustaka Utama, Jakarta.

Randall, J.E., Allen, G.R. and Steene, R.C., 1990. Fishes of the Great Barrier Reef and Coral Sea. Crawford House Press, Bathurst (Australia).

Randall, J.E. and Randall, H.A., 1987. Annotated checklist of fishes of Enewetak Atoll and Other Marshall Islands. In Vol 2. The natural History of Enewetak Atoll. Office of Scientific and Technological Information U.S. Dept. of Energy: 289-324.