VARIABLE PATTERNS OF DEN HABITATION BY THE ORNATE ROCK LOBSTER, PANULIRUS ORNATUS, IN THE TORRES STRAIT. Jasper Trendall and Stewart Bell

BULLETIN OF MARINE SCIENCE, 45(3): 564-573, 1989 VARIABLE PATTERNS OF DEN HABITATION BY THE ORNATE ROCK LOBSTER, PANULIRUS ORNATUS, IN THE TORRES STRAIT Jasper Trendall and Stewart Bell ABSTRACT Tagging and visual surveys by divers were used to investigate patterns of den habitation by Panu/irus ornatus (Fabricius) in Torres Strait. Several locations representing two distinct habitats and, consequently, den types were sampled. On the shallow reef-tops, lumps of coral or rock form "rock" dens, offering fixed, permanent shelter. Along reef edges and in deeper water, shallow holes in loose coral rubble form "rubble" dens, which offer temporary shelter. The lobsters showed two different patterns of den habitation. Where "rock" dens were the principal type, the lobsters were gregarious: over 70% were found in groups of two or more. In areas in which "rubble" dens predominated, almost all the lobsters were solitary. Recaptures of tagged animals indicated that few rock lobsters moved between reef systems more than 5 km apart. However, they appeared to move regularly between dens and between areas within any single reef system. Consequently, the distribution of lobsters among the dens on the reef was variable. The ornate rock lobster, Panulirus ornatus, is found throughout the Indo-Pacific but is particularly abundant in Torres Strait, between Australia and Papua New Guinea (George, 1968). It is the basis of important commercial fisheries in both countries, and approximately 200-300 t(tail weight) of rock lobsters are taken from Torres Strait each year (Channells, 1986). The rock lobsters are distributed widely among the reefs in the area. They shelter in dens in the rock and coral of the reefs during the day, leaving these dens at night to feed. Panulirus ornatus does not readily enter pots or traps and, in Torres Strait, they are caught by divers using Hawaiian-sling spears. This fishing method is labor intensive because the divers must search for the lobsters in their dens. The distribution of the rock lobsters on the reef determines the effectiveness of any particular search pattern and, ultimately, the catch of the fishermen. This study examined the distribution and den habitation patterns of P. ornatus in a number of shallow and deep areas near Warrior Reef in Torres Strait. In Torres Strait, P. ornatus has an annual breeding emigration, in which juvenile lobsters about 3 years old leave the reefs and walk north-east to the Gulf of Papua to breed (Moore and MacFarlane, 1984; MacFarlane and Moore, 1986; Prescott et al., 1986). The present study describes the behavior of lobsters 60-130 mm CL (carapace length) (between 2 and 3 years old) that have entered the commercial fishery, but have not yet left the reefs on the annual breeding emigration. METHODS AND MATERIALS Sampling was undertaken at four locations (Fig. I), representing areas of shallow water fished by free-divers using snorkel gear (Tudu Lagoon and Marakai Reef) and areas of deeper water fished by hookah-divers using compressed air (Zagai Island and Hookah Edge). At Tudu Lagoon and Marakai Reef, the depth of water varied between 3 and 6 m, depending upon the state of the tide. Surveys at these locations were made by free-diving. At the other locations where the water depth was between 3 and 20 m, we used a hookah compressed-air unit. Most of the work was carried out between June and November 1985, with some additional data collected between June and October 1986. Den Types. - In this study all dens were classified into two broad categories: I) "rock" dens, which are caves or crevices in lumps of coral or rock. They can accommodate one or more lobsters; the 564

TRENDALLANDBELL:DENHABITATIONBYPANULIRUS ORNATUS 565 go 40' S 143 E MARAKAI REEF go 50 ZAGAI b ~. HOOKAH EDGE ~ Figure I. Map of the study area showing the location of the principal sampling sites. larger lumps of coral can be over a meter high and several meters in circumference and are known coloquially as "bommies" (Fig. 2a). They provide permanent, stable shelter. 2) "rubble" dens are shallow holes in loose coral rubble, often near a small, isolated outcrop of rock or coral (Fig. 2b). This category was generally easily recognizable, but if the distinction between a rock and rubble den was unclear, the den was classified as a "rock" den. Tagging. - Lobsters at Tudu Island and Marakai Reef were captured, measured, tagged and then released in the vicinity of the site of capture. Lobsters larger than 70 mm CL were tagged with western rock lobster tags (ChittJeborough, 1974), and lobsters smaller than 70 mm CL were marked with "Hallprint" anchor tags (Hall print Pty. Ltd., South Australia). The tags were inserted into the musculature on one side of the mid-dorsal line between the carapace and the first abdominal segment. A separate tagging survey using external antennal tags was carried out over six days in a small area of "rock" dens adjacent to Tudu Lagoon. Epoxy resin and adhesive tape were used to attach numbered plastic tags to the antenna. These tags, which lasted at least a week and which did not appear to induce nomadism (TrendalI, 1989), were applied underwater without removing the lobster from its den. All dens in the area were identified and the number of marked and unmarked occupants in each den recorded daily. This technique enabled us to monitor the movements of individual animals. Visual Surveys. - The num ber of rock lobsters in each den and hence the abundance of lobsters in the survey area was recorded by a diver. At the same time, sizes were estimated and these data refer to lobsters between 60 and 130 mm CL. Males and females could not be consistently identified in the field and the sexes have been pooled. Two methods were used: den surveys of specific, individually identified dens and area surveys of larger areas (e.g., Marakai Reef) or where strong currents or poor visibility made navigation difficult (e.g., Hookah Edge). DEN SURVEYS.In Tudu Lagoon and at Zagai Island, individual dens were identified, marked with numbered plastic streamer tape and then re-sampled regularly, often daily. At Tudu Lagoon, all the dens were identified and marked at the beginning of the study. A shelter was classified as a den if it was occupied in the initial survey; only these dens were surveyed subsequently. At Zagai Island, a shelter was classified as a den ifit had an occupant, but surveys were not

566 BULLETIN OF MARINE SCIENCE, VOL. 45, NO.3, 1989 Figure 2. Panulirus ornatus. Photographs of a lobster in a "rock" den (a) and a "rubble" den (b). restricted to the initial set of dens because there was a higher rate of transient occupancies in this study area than at Tudu Lagoon. If a lobster was present in a shelter that had not been occupied previously, a new den was recorded. As a result, each survey usually recorded an increase in both the total number of dens and the number of vacant dens. The results from the surveys at Tudu Lagoon and Zagai Island are, therefore, analyzed separately.

TRENDALLANDBELL:DENHABITATIONBYPANULIRUSORNATUS 567 SOUTH CENTRAL NORTH / N 1km Figure 3. Map of Marakai Reef showing a shallow sand-bank (stippled) and the arbitrary division of the western half of the surrounding reef-flat into three sampling areas (South, Central, North). The relative positions of the four quadrats (50 m x 50 m) are also indicated. AREASURVEYS.These were made at Marakai Reef and Hookah Edge. Unlike the den surveys, the area surveys sampled the rock shelters on the reef on the basis of their potential as dens, and not their previous occupancy by lobsters. The shelters censused were selected visually from a boat, in the same way that commercial divers select suitable shelters for fishing. Although there was no means of telling whether an apparently suitable site had ever been occupied by lobsters, this sampling method will not necessarily bias the results. At Marakai Reef, buoys were used to divide the reef-top into three approximately equal areas (Fig. 3). Half-hour surveys were carried out in the north and central areas only, because there was very little shelter in the south area. No attempt was made to return to the same shelters and each survey was an independent sample of the available shelters. At Marakai Reef, four 50 m. 50 m quadrats were laid out in the north and central sections of the reef flat (Fig. 3). The quadrat sites were selected to represent areas of typical shelter and in each case at least one lobster was present when the quadrat was first marked. The quadrats were censused for 21 days between 23 September and 29 October 1985. The number of lobsters in each quadrat was counted and the dens marked and recorded. Removal of Residents. - For 29 consecutive days in July and August 1985, all resident lobsters were caught from three rock dens in Tudu Lagoon and were removed from the area. The rate at which these dens were re-occupied by new lobsters provided estimates of the number of individuals utilizing a particular den and the frequency of movement between dens. RESULTS Large Scale Movements.-Between June and October 1985, 1,095 rock lobsters were tagged at Tudu Island and Marakai Reef. By October 1986, 185 had been recaptured, mainly in the area in which they had been released. Of the 953 lobsters tagged at Tudu Island, 169 (17%) were recaptured, all but 9 within 5 km of the island. Six animals had moved approximately 10 km north, to the main Warrior Reef system and three lobsters that had taken part in the breeding emigration were recaptured in the Gulf of Papua, as far as 400 km to the northeast. Of the 142 lobsters tagged at Marakai Reef, 16 (11.3%) were recaptured. Only three had moved away from Marakai Reef: two were recaptured at the southern end of Warrior Reef, in the vicinity of Tudu Island, and one animal was caught approximately 20 km away, on the eastern edge of Warrior Reef. Distribution and Den Occupancy. -ROCK DENS. The typical pattern of "rock" den occupancy is illustrated in Figure 4 in Tudu Lagoon and Marakai North. Approximately 60% of dens were empty; less than 20% were occupied by a single

568 BULLETIN OF MARINE SCIENCE, VOL. 45, NO.3, 1989 TUDU LAGOON TUDU LAGOON n-39 days 1248 records 60 n,39 days 1270 records 40 <I) C <Jl c 20 '0 '" OJ C '0 10 '0 <I) Q; MARAKAI NORTH " <I) D '" ~ g OJ 60 n 36 days Q. 769 records '0 40 20 C '" u Q; Q. 20 10 MARAKAI NORTH n=35 days 878 records 0 2 3 4-6 7-9 2 3 4 6 79 10+ No. of lobsters per den No. of lobsters per den Figure 4. (left) Panu/irus ornatus. Mean daily percentage of dens with 0, I or more lobsters at two "rock" den sites. Error bars indicate + 1 SE of mean. Figure 5. (right) Panu/irus ornatus. Mean daily percentage of lobsters found singly or in groups at two "rock" den sites. Error bars indicate + 1 SE of mean. lobster; and the rest were occupied by two or more animals. The tendency for more than one lobster to shelter in a den suggests that they are gregarious. More than 70% of the lobsters observed at Tudu Lagoon and Marakai Reef were found in groups of two or more (Fig. 5). The rate of occupancy of dens in Tudu Lagoon and Marakai North was not significantly different (Fig. 4, Kolmogorov-Smirnov two sample test, Dmax= 0.286, P = 0.167), and neither was the distribution of lobsters (Fig. 5, Kolmogorov-Smirnov two sample test, Dmax= 0.333, P = 0.109). However, fewer large (10 +) groups were observed in Marakai Central than in Marakai North (Kolmogorov-Smirnov two sample test, Dmax= 0.417, P= 0.021), though neither the rate of den occupancy nor the distribution of the lobsters was different. Some rock dens were occupied by more lobsters than others. The mean number oflobsters per den during the sampling period was recorded. This number reflects not only the physical capacity of the den but also the frequency with which it is occupied. From the point of view of a fisherman, the greater the mean number of occupants, the "better" the den. However, dens with a high mean number of residents were not occupied all the time. In Tudu Lagoon, in a set of 36 dens sampled on 20 different days, all the dens were vacant at least 20% of the time, and even dens that were capable Ofholding large numbers oflobsters were occupied by groups of three or more lobsters less than half the time (Fig. 6).. "RUBBLE" DENS. At the locations where rubble dens were most common, the distribution of the lobsters was different from that in rock den areas. Instead of being found in groups, more than 70% of animals were solitary (Fig. 7). This pattern of den occupancy at both Zagai and Hookah Edge was significantly different from that observed at Tudu Lagoon or Marakai North (Kolmogorov-Smirnov two sample test, Dmax= 0.667, P < 0.003). A predominance ofsingle dens is to be expected where the shelters are shallow and loosely formed. At Zagai, in a series of nine samples over a period of 8 weeks, approximately 45% of the dens that were marked were observed to be occupied only once. Few dens were occupied for long and no dens had resident lobsters for more than six of the nine samples

TRENDALL AND BELL: DEN HABITATION BY PANULIRUS ORNATUS 569 en >-. 36 dens ctl 90.". "0.. 20 days OJ c: 70 a.... E. ctl en 50... '0..0 30 0 c: 0 ~. Q) 0 t>... 'bo Q) 10 0 o 0 0 0:> a.. o 00 «qj - - 0.8 1.6 2.4 3.2 Mean no. of lobsters per den Figure 6. Panulirus ornatus. Relation between the mean number of lobsters in "rock" dens in Tudu Lagoon and the occupancy pattern of the den. For each den, the percentages of sampling days it was unoccupied (.) or occupied by three or more lobsters (O) are indicated. (Fig. 8). The rubble dens were used as temporary shelters, with little or no continuity of occupancy. Local Movements and Den Fidelity. -In all locations the occupancy pattern of individual dens, whether rock or rubble, was unpredictable, with the lobsters often moving daily. This was most clearly observed in quadrats at Marakai Reef. Although there was an overall mean of about 6 residents per day, the number of occupants varied between 1 and 18 lobsters per day (Table 1). At the same time as the quadrats were sampled, surveys were carried out in the north and central areas of Marakai Reef, the areas in which the quadrats were sited. The numbers oflobsters observed on any given day, in the survey areas or the quadrats, were not correlated (North area vs. Central area, N = 26, r 2 = 0.115; quadrats vs. North and Central areas, N = 16, r 2 = 0.001). This indicates that the daily, local changes in abundance in the quadrats and sampling areas on Marakai Reef did not reflect uniform large-scale changes in the number of lobsters on the reef-top. Within the quadrats the lobsters appeared to be opportunistic in their utilization of den sites. For example, in quadrat C only five of the nine dens were occupied on any given day (Table 2). None of the dens was occupied for more than 10 consecutive days, and it seems likely that, even if the lobsters have a set of "home" dens, different lobsters utilize the same dens at different times. The removal experiment and the antennal tagging provided two further pieces of evidence that den fidelity is not apparent in Panulirus ornatus. All resident lobsters were removed each day for 29 days from three rock dens in Tudu Lagoon, giving totals of 13, 18 and 20 lobsters. The largest number of lobsters removed from a single den on 1 day was six, and 73% of the occupants were found either alone or in pairs. Many more lobsters used each den than were ever found occupying it on any single day. This suggests that, regardless of whether individuals are moving between home dens, the lobsters move frequently and have abundant shelter. Of 32 lobsters identified with antennal tags, only one occupied the same den on each of the 6 days of the study. Five other tagged animals that were subsequently observed in the study area had moved between dens within the study area and moved freely into and out of the survey area. The remaining 26 tagged lobsters

570 BULLETIN OF MARINE SCIENCE, VOL. 45, NO.3, 1989 70 50 ZAGAI n.10 days 236 records ",30 ~ "' 10.c.2 '0 C <l) u 70 a; Cl. 50 30 10 2 3 HOOKAH EDGE n.40days 388 records No. of lobsters per den 4-6 7-9 10+ '0 No of dens sampled Q) 86-. a. ::J 40 U u 0 :(l30 86 "'!: -a. 76 ~ ~20 '0 = "' 10 59 - '" 41 28!: ~ 22 13 <l) 0 0 ~- Cl. '" 2 3 4 5 6 7 8 9 No. of times dens were sampled Figure 7. (left) Panu/irus ornalus. Mean daily percentage oflobsters found singly or in groups at two "rubble" den sites. Error bars indicate ± I SE of mean. Figure 8. (right) Panu/irus ornatus. Percent of "rubble" dens at Zagai that were occupied on one or more occasions in nine samples taken over a 60-day period. The number of dens sampled one or more times is indicated next to each point. were not seen again. During the study, a total of 64 lobsters were observed occupying 27 different dens in the study area. Although some dens consistently sheltered more lobsters than others, they were occupied by different individuals on different days. DISCUSSION A high proportion of tag returns from the areas in which lobsters were released has been reported in another tagging study of Panu/irus ornatus (Moore and MacFarlane, 1984). Tudu Lagoon and Marakai Reef are only about 12 km apart. Although both locations were fished heavily, and were the principal sites for tag recaptures, only 2 of 185 recaptured lobsters had moved between the reefs. It seems likely, therefore, that lobsters infrequently move between adjacent reef systems. Tagging studies of several other palinurids have shown a similar pattern of small, local «20 km) movements, e.g., Panu/irus homarus homarus (Mohamed and George, 1968), P. cygnus (Chittleborough, 1974), Jasus edwardsii (Annala, Table I. Panu/irus ornalus. The mean number and range of rock lobsters observed in each of four 50 x 50 m quadrats at Marakai Reef over a 3-week period (standard errors in parentheses) A B C 0 Pooled Days sampled (No.) 21 22 22 22 21 Lobsters (x) l.l 0.6 3.8 1.3 6.4 (0.2) (0.2) (0.6) (0.2) (0.9) Range 0-4 0-3 0-11 0-4 1-18

TRENDALL AND BELL: DEN HABITATION BY PANULIRUS ORNATUS 571 Table 2. Panulirus ornatus. The distribution of rock lobsters among the dens within Quadrat C at Marakai Reef Den Lobsters Date 4 6 9 (No.) (1985) 24 Sept 3 1 7 26 6 2 11 28 2 2 5 6 Oct 5 1 9 7 I 1 3 8 1 I 9 2 2 1 6 10 1 3 11 I 2 I 6 12 2 5 14 I 2 15 3 16 2 17 2 18 2 19 2 2 20 3 1 I 5 21 2 1 I 4 22 I I 23 2 2 28 1 1981) and some populations of P. argus (Little, 1972; Herrnkind, 1980). In the two species that have been studied most intensively (P. cygnus and P. argus), local movements appear to be associated with well-developed homing capabilities. They move regularly between feeding grounds and one or more home dens up to several hundred meters apart (Creaser and Travis, 1950; Chittleborough, 1974; Herrnkind and Redig, 1975; Herrnkind et al., 1975; Cobb, 1981; Jernakoff, 1987). Panulirus cygnus is highly gregarious. Chittleborough (1974) and Cobb (1981) reported that over 70% of occupied dens had two or more lobsters, and some had well over 50 residents. In one area, Cobb (1981) found sole occupants in only 3% of occupied dens. P. argus is less gregarious: in the Bahamas, Herrnkind et al. (1975) reported that between 19 and 45% of the lobsters were sole occupants. However, the majority oflobsters of both species occupy multiple residency dens and, more importantly, apparently are principally found in dens in hard substrata (i.e., rock dens) (Herrnkind et al., 1975; Davis, 1977; Cobb, 1981). Panulirus ornatus in Torres Strait differs from P. cygnus in particular because it is not restricted to dens in hard substrata but opportunistically utilizes temporary shelters in loose coral rubble. A similar pattern of den occupancy has been observed in P. argus (Davis, 1977) and other workers in Torres Strait have commented that P. ornatus is frequently found sheltering in small holes in areas offering little cover (Moore and MacFarlane, 1984). In the areas where rubble dens were common, the den habitation pattern of P. ornatus was predominantly solitary. There was no evidence that lobsters occupying rubble dens had been excluded from rock dens. At both Tudu Lagoon and Marakai Reef, there were more unoccupied than occupied dens. At Zagai and Hookah Edge, where rubble dens were adjacent to areas with rock dens, the rock dens were often vacant. There were

572 BULLETIN OF MARINE SCIENCE, VOL. 45, NO.3, 1989 also large areas of coral rubble in which lobsters were rarely found. The presence of lobsters in an area does not appear to be determined by the physical characteristics of the shelter. The gregarious pattern of den habitation shown by Panulirus ornatus in the rock dens is comparable to that of other palinurids. In spiny lobsters the frequency of multiple occupancy dens is determined by a complex of factors, including population density, behavioral interactions and the physical qualities of dens (Herrnkind et al., 1975; Cobb, 1981; Zimmer-Faust et al., 1985). Aggregation may be advantageous in more efficiently excluding predators from dens (Berrill, 1975; Cobb, 1981), in facilitating predator detection and avoidance (Berrill, 1975; Zimmer-Faust et al., 1985) and optimizing shelter and food resources (Atema and Cobb, 1980; Cobb, 1981). These explanations are applicable to the den habitation pattern of P. ornatus in rock dens, but are difficult to reconcile with the solitary den occupancy shown by P. ornatus in rubble dens. The lobsters' use of rubble dens demonstrates that the animals are not completely dependent upon the physical characteristics of rock dens or the advantages offered by gregarious den occupancy. Field observations in this and earlier work (Heasman and Ryall, unpublished) have suggested that large Panulirus ornatus and the occupants of rubble dens are more likely to leave a den when threatened than to follow the usual escape response of retreating into the shelter. Possibly the strong currents and turbid waters of the Torres Strait increase the effectiveness of swimming as an escape response for P. ornatus. The lobsters would, therefore, not be as reliant on dens for physical shelter and would be able to utilize habitats, such as coral rubble, in which there are few structurally adequate dens. Regardless of whether the lobsters were occupying rock or rubble dens, their distribution was unpredictable. They rarely moved between reef systems, but regularly moved between dens, and the number of lobsters resident in any particular den or small area varied from day to day. Without diving on the reef and searching the dens, fishermen cannot tell whether a particular area is going to be rewarding or not. Local knowledge will assist individual divers in choosing the dens that are perceived to be most productive. However, on average, 60% of all dens were vacant and even the "best" dens on the reef were unoccupied for approximately 20% of the time. As a result, searching will always be an important component of the fishing effort for divers. ACKNOWLEDGMENTS The authors particularly thank C. Turnbull, L. Squires and J. Beckman for help with fieldwork and J. Bell for laboratory work. B. Phillips provided valuable advice throughout the work, and J. Booth, P. Jernakoff and A. MacDiarmid substantially improved initial drafts of the manuscript. R. Ralph and L. Brooks provided constant and vital field support. This work was undertaken by the CSIRO Tropical Rock Lobster Project in Cairns and was funded by the Department of Primary Industry and Energy, Torres Strait Research Fund. LITERATURE CITED Annala, J. H. 1981. Movements of rock lobsters (Jasus edwardl'ii) tagged near Gisborne, New Zealand. N.z. J. Mar. Freshwat. Res. 15: 437-443. Atema, J. and J. S. Cobb. 1980. Social behavior. Pages 409-450 in 1. S. Cobb and B. F. Phillips, eds. The biology and management oflobsters. Vol. 1. Academic Press, New York. Berrill, M. 1975. Gregarious behavior of juveniles of the spiny lobster, Panu/irus argus (Crustacea: Decapoda). Bull. Mar. Sci. 25: 515-522. Channells, P. 1986. History and development of the Australian rock lobster fishery for Panu/irus

TRENDALL AND BELL: DEN HABITATION BY PANULlRUS ORNATUS 573 ornatus. Pages 84-189 in A. K. Haines, G. C. Williams and D. Coates, eds. Torres Strait fisheries seminar, Port Moresby, 1985. Aust. Govt. Publ., Canberra. Chittleborough, R. G. 1974. Home range, homing and dominance in juvenile western rock lobsters. AusL J. Mar. Freshwat. Res. 25: 227-234. Cobb, J. S. 1981. Behaviour of the western Australian spiny lobster, Panulirus cygnus George, in the field and laboratory. Aust. J. Mar. Freshwat. Res. 32: 399-409. Creaser, E. P. and D. Travis. 1950. Evidence of a homing instinct in the Bermuda spiny lobster. Science II: 169-170. Davis, G. E. 1977. Effects of recreational harvest on a spiny lobster, Panulirus argus, population. Bull. Mar. Sci. 27: 223-236. George, R. W. 1968. Tropical spiny lobsters, Panulirus sp., of western Australia (and the Indo-West Pacific). J. Roy. Soc. W. Aust. 51: 33-38. Herrnkind, W. F. 1980. Spiny lobsters: patterns of movement. Pages 349-407 in J. S. Cobb and B. F. Phillips, eds. The biology and management oflobsters. Yol. I. Academic Press, New York. --- and M. X. Redig. 1975. Preliminary study of establishment of den residency by spiny lobster, Panulirus argus, at Grand Bahama Island. Hydro-Lab. J. 3: 96-101. ---, J. A. YanDerwalker and L. Barr. 1975. Results ofthe Tektite program: population dynamics, ecology and behavior of spiny lobsters, Panulirus argus. of St. John, U.S.Y.I.: (IV) Habitation, patterns of movement and general behavior. Nat. Hist. Mus. Los Ang. Cty Sci. Bull. 20: 31-45. Jernakoff, P. 1987. Foraging patterns of juvenile spiny rock lobsters, Panulirus cygnus, George. J. Exp. Mar. BioI. Ecol. 113: 124-144. Little, E. J. 1972. Tagging of spiny lobsters (Panulirus argus) in the Florida Keys, 1967-1969. Fla. Dep. Nat. Resour. Mar. Res. Lab. Spec. Sci. Rep. 31. 23 pp. Mohamed, K. H. and M. J. George. 1968. Results of the tagging experiments on the Indian spiny lobster, Panulirus homarus (Linnaeus)-movement and growth. Ind. J. Fish. 15: 15-26. MacFarlane, J. W. and R. Moore. 1986. Reproduction of the ornate rock lobster, Panulirus ornatus (Fabricius), in Papua New Guinea. Aust. J. Mar. Freshwat. Res. 37: 55-65. Moore, R. and J. W. MacFarlane. 1984. Migration of the ornate rock lobster, Panulirus ornatus (Fabricius), in Papua New Guinea. AuSL J. Mar. Freshwat. Res. 35: 197-212. Prescott, J. H., B. F. Phillips and R. S. Bell. 1986. Rock lobster research in Torres Strait. Aust. Fish. 45: 2-4. Trendall, J. 1989. Influence of tag type on recapture rates in the tropical rock lobster, Panulirus ornatus. Bureau Rural Resources Proc. 5: 68-76. Zimmer-Faust, R. K., J. E. Tyre and J. F. Case. 1985. Chemical attraction causing aggregation in the spiny lobster, Panulirus interruptus (Randall), and its probable ecological significance. BioI. Bull. 169: 106-118. DATEACCEPTED: November 14, 1988. ADDRESS: (J.T.) CSIRO Division oj Fisheries Research, Bungalow P.O.. Cairns, Queensland 4870. Australia; PRESENT ADDRESSES: (J.T.) Australian Independent Research. P.O. Box 7197, Cairns, Queensland 4870. Australia; (S.B.) P.O. Box 50, Woodbridge, Tasmania 7162, Australia.