Fish predators of the western rock lobster (Panulirus cygnus George) in a nearshore nursery habitat

1988 ◽  
Vol 39 (3) ◽  
pp. 307 ◽  
Author(s):  
RK Howard
Keyword(s):  
Fish Species ◽  
Fish Community ◽  
Carapace Length ◽  
Nursery Habitat ◽  
Rock Lobster ◽  
Lack Of Information ◽  
Gill Net ◽  
Fish Predators ◽  
Panulirus Cygnus ◽  
A Current

Nearshore limestone reefs of Western Australia represent an important nursery habitat for juveniles of the western rock lobster (Panulirus cygnus). As part of a trophic study of the fish community associated with these reefs, fishes were examined for evidence of predation on western rock lobsters. Six fish species were found to have ingested P. cygnus. Of these, Psammaperca waigiensis (sand bass), Pelsartia humeralis (sea trumpeter), Pseudolabris parilis (brown-spotted wrasse) and Plectorhyncus flavornaculatus (gold-spotted sweetlips) were among the ten most abundant fish in gill-net collections from the study site. P. cygnus formed a significant portion of the diet of P. waigiensis, but was < 5% of the dietary volume of other species. Predation occurred at all times of the day and was concentrated on small, newly-settled P. cygnus (8-15 mm carapace length). The vulnerability of lobsters to predation appears to be strongly related to size, and the cryptic habits that are unique to newly-settled stages can be explained in terms of the risks of predation. Assessment of the proportion of mortality of P. cygnus due to predation is hampered by a current lack of information on the natural densities of both fishes and small rock lobsters. However, conservative estimates indicate that an annual removal by fish of thousands of lobsters per hectare is likely, suggesting that predation is a major factor affecting the survival of P. cygnus on nursery reefs.

Increased density, biomass and egg production in an unfished population of Western Rock Lobster (Panulirus cygnus) at Rottnest Island, Western Australia

2007 ◽  
Vol 58 (3) ◽  
pp. 286 ◽  
Author(s):  
R. C. Babcock ◽  
J. C. Phillips ◽  
M. Lourey ◽  
G. Clapin
Keyword(s):  
Western Australia ◽  
Carrying Capacity ◽  
Egg Production ◽  
Carapace Length ◽  
Spiny Lobster ◽  
Shallow Waters ◽  
Recreational Fishing ◽  
Total Biomass ◽  
Rock Lobster ◽  
Panulirus Cygnus

Surveys of spiny lobster (Panulirus cygnus) populations in shallow waters surrounding Rottnest Island in Western Australia revealed much higher levels of density, biomass and egg production in no-take than in fished areas. Density of lobsters was ~34 times higher in the sanctuary, and density of lobsters above minimum legal size around 50 times higher than in other areas around the island where recreational fishing is allowed. Mean carapace length (CL), total biomass and egg production of lobsters in the sanctuary zone were significantly higher than in adjacent fished areas. Large individuals (≥100 mm CL), especially large males, were found almost exclusively within the sanctuary. The abundance of mature animals in these shallow waters indicates that not all P. cygnus migrate to deep water and that shallow water habitats may currently be well below carrying capacity in terms of biomass and egg production. If implemented in a systematic way, unfished areas such as the Kingston Reefs could also provide a useful fisheries-independent tool for assessing trophic interactions and the structure and density of unfished populations, and for estimating parameters such as growth of larger individuals that may be rare or absent in more widely fished populations.

Spatial Model for the Population Dynamics and Exploitation of the Western Australian Rock Lobster, Panulirus cygnus

1993 ◽  
Vol 50 (8) ◽  
pp. 1650-1662 ◽  
Author(s):  
Carl J. Walters ◽  
Norm Hall ◽  
Rhys Brown ◽  
Chris Chubb
Keyword(s):  
Carapace Length ◽  
Temporal Dynamics ◽  
Population Analysis ◽  
Fishing Effort ◽  
Management Policy ◽  
Rock Lobster ◽  
Breeding Grounds ◽  
Panulirus Cygnus ◽  
Biological Assessments ◽  
Western Australian

There is concern about whether long-standing regulatory measures (size and effort limits) are adequate to protect spawning stocks of the Western Australian rock lobster, Panulirus cygnus, and assure the highest average yields. Virtual population analysis and tagging studies indicate that exploitation rates are extremely high (possibly exceeding 70%/yr) on younger, mainly immature lobsters. To predict the efficacy of alternative regulatory schemes, it has been necessary to explicitly model the spatial and temporal dynamics of lobster abundance and fishing effort. Puerulus settlement (at age 9–11 mo) is mainly into shallow-water (< 40 m) areas, and at 3–5 yr of age in most areas, there is a migration into deeper water where the animals mature after a further 1–2 yr. The size at migration (70–90 mm carapace length) ensures that at least some animals will have a chance to reach the breeding grounds offshore, where fishing effort has historically been lower than inshore, before they reach the minimum legal size (76 mm carapace length). By explicitly modelling the effort distribution as well as lobster movement and stock distribution, we hope to anticipate some consequences of changes in management policy that could not be predicted from biological assessments alone.

scholarly journals The hydraulic management of the Barra Bonita reservoir (SP, Brazil) as a factor influencing the temporal succession of its fish community

2007 ◽  
Vol 67 (3) ◽  
pp. 433-445 ◽  
Author(s):  
ML. Petesse ◽  
M. Petrere Jr. ◽  
RJ. Spigolon
Keyword(s):  
Fish Species ◽  
Fish Community ◽  
Abundant Species ◽  
Anthropogenic Stress ◽  
Reservoir Level ◽  
Species List ◽  
Adaptation Capacity ◽  
Reproductive Structures ◽  
Temporal Succession ◽  
Reproductive Compensation

The temporal succession of fish communities allows evaluating the environmental conditions and the adaptation capacity of the fish species to anthropogenic stress in reservoirs. The fish community at Barra Bonita reservoir was sampled in two different periods of the year (dry and rainy) and in three different areas of the reservoir (fluvial, transition, and lentic). The species list was compared to another four lists, trying to detect the transformations of the fish community for the last 15 years. In order to evaluate the adaptation of the present fish community to the hydraulic management of reservoir, the trophic and reproductive structures were studied. Temporal succession analysis shows little change in fish richness of the communities. The number of fish species varies between 23 and 39 for a total of 68 registered species. From this, 27 can be considered constant, 14 accessory and 27 accidental; the main differences observed were for Anostomidae, Loricariidae and Characidae families. In relation to the hydraulic management, we found a fish community stabilized and adapted to environmental stress. This is characterized by the dominance of small-sized fish species of opportunistic diet and high reproductive compensation (r-strategists). The overlap of biological cycles of the most abundant species with the reservoir level fluctuations points to the period from September to March-April as critical for reproductive success and only the species with partial reproductive strategy or parental care are best succeeded. These results, interpreted in the context of the reservoir aging process, indicate that Barra Bonita reservoir is entering a transition phase, between the colonization and aging stages.

scholarly journals Keanekaragaman Jenis Ikan di Hilir Sungai Sekadau Kalimantan Barat

2019 ◽  
Vol 8 (2) ◽  
Author(s):  
Kristoforus Slamet Suryadi Junardi, Tri Rima Setyawati
Keyword(s):  
Data Collection ◽  
Fish Species ◽  
Environmental Conditions ◽  
West Kalimantan ◽  
Gill Net ◽  
Distribution Of Fish

Diversity of fish species is important  known to determinate river. The purpose of this study was to determine the diversity and distribution of fish also environmental conditions in the lower reaches of the Sekadau River, West Kalimantan. Data collection is conducted from March to May 2018 using posat and gill net. The results showed that the most common Cyprinidae family was found in Rasbora argyrotaenia  and Osteochilus microcephalus with dominance value  0.72 and 0.70 respectively.

Status of fish biodiversity and fishing on Hau River, Mekong Delta, Vietnam

2020 ◽  
Vol 56 ◽  
pp. 14
Author(s):  
Vu Ngoc Ut ◽  
Au Van Hoa ◽  
Huynh Phuoc Vinh
Keyword(s):  
Species Composition ◽  
Fish Species ◽  
Mekong Delta ◽  
Middle Part ◽  
Fishing Ground ◽  
Sampling Gear ◽  
Fish Biodiversity ◽  
Gill Net ◽  
Fishing Gears ◽  
The Status

Fish biodiversity on Hau (Bassac) river was investigated to assess the status of species composition and fishing by fishing gears during a year. Sampling was implemented monthly at the upper part (An Giang province), middle part (Can Tho City) and lower part (Soc Trang province) of Hau River using trawl net as main sampling gear. Additionally, fish composition was also recorded from four other most popular fishing gears including cast net, gill net, fixed net and hook operated in the study sites. Fish species composition was determined by fishing gears and their abundance (CPUE) was calculated only from the main sampling gear (trawl net). The results showed that a total of 176 fish species belonging to 16 orders and 49 families was recorded. Perciformes was the most abundant group with 51 species followed by Cypriniformes with 46 species. The number of fish species was decreasing from upper part to lower part. Trawl net was considered the most destructive gear as up to 145 fish species caught by this device, followed by gill net with 98 species, fixed net 75, cast net 57, and hooks 16 species. CPUE was very low ranging from  0.53 kg.ha−1 h−1 to 26.30 kg.ha−1 h−1. Higher CPUE was recorded at lower part in compared to upper part and middle part, and at dry season in compared to rainy season. Regulation on fishing gears, fishing ground and season should be taken into consideration to protect and conserve the resources.

scholarly journals Stocking density and shelter type for the optimal growth and survival of western rock lobster Panulirus cygnus (George)

Aquaculture ◽  
2006 ◽  
Vol 260 (1-4) ◽  
pp. 114-127 ◽  
Author(s):  
Danielle Johnston ◽  
Roy Melville-Smith ◽  
Blair Hendriks ◽  
Greg B. Maguire ◽  
Bruce Phillips
Keyword(s):  
Stocking Density ◽  
Optimal Growth ◽  
Rock Lobster ◽  
Growth And Survival ◽  
Panulirus Cygnus

Spatial and temporal variation in lipid and fatty acid profiles of western rock lobster pueruli at first settlement: biochemical indicators of diet and nutritional status

2009 ◽  
Vol 60 (8) ◽  
pp. 810 ◽  
Author(s):  
A. J. Limbourn ◽  
R. C. Babcock ◽  
D. J. Johnston ◽  
P. D. Nichols ◽  
B. Knott
Keyword(s):  
Fatty Acid ◽  
Nutritional Status ◽  
Spatial And Temporal Variation ◽  
Lipid Levels ◽  
Rock Lobster ◽  
Important Species ◽  
Fa Composition ◽  
Lipid Fatty Acid ◽  
Spatial And Seasonal Variation ◽  
Panulirus Cygnus

Rock lobster species are found worldwide and have a life history that includes development through a planktonic phyllosoma followed by a nektonic non-feeding puerulus that relies on stored energy during recruitment into near-shore habitats. Recruitment to adult populations of western rock lobster (Panulirus cygnus) is highly variable and is likely to be strongly influenced by shelf width and oceanic conditions affecting cross-shelf transport and nutrition. Since the nutritional status of newly settled pueruli will reflect the phyllosoma feeding environment and distance swum, we studied levels of lipid, fatty acid (FA) and protein of 422 pueruli and 79 first instar juveniles from four Western Australian locations. Lipid levels generally were inversely related to shelf width but were variable, suggesting pueruli may travel complex trajectories to coastal settlement. Lipid and FA composition of pueruli were consistent with spatial and seasonal variation in Leeuwin Current and coastal productivity regimes. Seasonal differences in FA composition occurred regardless of the year of settlement. Pueruli had lower lipid levels during ENSO years, when recruitment tends to be lower also. Measures of puerulus nutritional status appear to provide valuable insights into the processes underpinning recruitment in Panulirus cygnus and other commercially and ecologically important species.

Genetic structure of the western rock lobster, Panulirus cygnus, with the benefit of hindsight

1996 ◽  
Vol 47 (7) ◽  
pp. 889 ◽  
Author(s):  
AP Thompson ◽  
JR Hanley ◽  
MS Johnson
Keyword(s):  
Genetic Structure ◽  
Western Australia ◽  
Allozyme Variation ◽  
Genetic Homogeneity ◽  
Latitudinal Variation ◽  
Rock Lobster ◽  
Polymorphic Loci ◽  
Allelic Frequencies ◽  
Genetic Subdivision ◽  
Panulirus Cygnus

Allozyme variation was used to investigate the genetic structure of the western rock lobster, Panulirus cygnus, along the coast of Western Australia. The study involved genetic surveys in 1980 and 1994. The first survey showed strong suggestions of latitudinal variation at two polymorphic loci, EST and GPI, but these suggestions were statistically suspect. With the benefit of hindsight gained from 1980, the 1994 survey was designed to examine more directly the suggestion of latitudinal genetic subdivision in this species. No evidence of genetic subdivision was found at either the EST or the GPI locus. In addition, the average FST value over nine polymorphic loci was a very low 0.0002. The evidence is consistent with current interpretations that P. cygnus is a single, panmictic population. In contrast with this spatial genetic homogeneity, however, there were significant changes in allelic frequencies at the GPI locus between 1980 and 1994, indicating genetic differences among cohorts.

Biological tags as moult indicators in Panulirus cygnus (George)

1997 ◽  
Vol 48 (8) ◽  
pp. 959 ◽  
Author(s):  
R. Melville-Smith ◽  
J. B. Jones ◽  
R. S. Brown
Keyword(s):  
Carapace Length ◽  
Size Range ◽  
Field Trials ◽  
Size Category ◽  
Fishing Season ◽  
Panulirus Cygnus ◽  
Biological Tags

Laboratory and field trials were employed to examine the feasibility of using biological tags as moult indicators. Twenty-four animals were tagged with epidermal implants and held in aquaria for 2 years and 8 months before the tags were removed. Five tags failed to form useful cysts and one tag was damaged during processing. The remaining 18 lobsters moulted between three and six times, with this moulting record being accurately verified by 15 of the biological tags and incorrectly interpreted (by one moult) in one case. Two tags produced inconclusive results. Biological tags were tested in the field in the Fremantle area, with 132 animals being recaptured out of 1336 tagged. Eleven tags proved impossible to read, eight failed to form cysts, and the balance recorded up to six moults during the release period. Animals in the size range 60–80 mm carapace length (CL) recorded two moults per year, one in February–April and a second before the mid-November start to the fishing season. Females grew significantly less per moult than did males in the same size category (60–85 mm CL), and both sexes showed significantly smaller increments for animals ≥85 mm CL at release.

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