Age validation, growth and mortality rates of the tropical snappers (Pisces: Lutjanidae) Lutjanus adetii (Castelnau, 1873) and L. quinquelineatus (Bloch, 1790) from the central Great Barrier Reef, Australia

1996 ◽  
Vol 47 (4) ◽  
pp. 575 ◽  
Author(s):  
SJ Newman ◽  
DM Williams ◽  
GR Russ

The age and growth of Lutjanus adetii and L. quinquelineatus from the central Great Barrier Reef were determined from studies of annuli in sectioned otoliths (sagittae). The period of annulus formation was validated by oxytetracycline labelling of externally tagged fishes. For L. adetii, validation was obtained from tagged fishes that were recaptured after a minimum of 12 months at liberty, the first time this has been achieved for a Lutjanus species. A single opaque and translucent zone was formed once a year, with the opaque band (annulus) being formed during the winter months. Otolith weight was strongly correlated with age for both species. There was significant differential growth between the sexes in length-at-age and weight-at-age for both species, with males growing larger than females. The oldest individuals found were a male L. adetii of 24 years of age and a female L. quinquelineatus of 31 years of age. The shape of the growth curves were steep for the first few years and then became asymptotic. The annual instantaneous rate of natural mortality (M) was 0.235 for L. adetii and 0.154 for L. quinquelineatus, representing an annual survivorship of 79% and 86%, respectively. The protracted longevity and low natural mortality rates imply that both L. adetii and L. quinquelineatus are vulnerable to overfishing despite their small size.

Author(s):  
Michael Kingsford ◽  
David Welch ◽  
Mark O'Callaghan

Patterns of age and growth of a sedentary damsel fish Acanthochromis polyacanthus were tested over a latitudinal range of approximately 10 degrees (1,200 km) on the Great Barrier Reef, Australia. Within latitudes these patterns were also compared on reefs across a continental shelf that ranged in width from 52 to 128 km. Although variation in length-max, growth, age-max and the von-Bertalanffy metrics of L, and K were found within and among latitudes, greatest variation in some demographic characteristics were found across the shelf regardless of latitude. Fish were always smaller at inner shelf reefs and grew more slowly when compared to mid and outer shelf reefs. The oldest fish collected was 11 years old and, there were no consistent variation in age-max among distances from shore. On outer reefs, there was a linear relationship with age-max and latitude. This ‘tropical gradient’ of age only explained 34% of the variation, further this was not found when the oldest 10% of fish were considered. Fish only reached an age-max of 6 years on the southern-most reefs. There was a trend for a smaller L with latitude but, it was not significant and L did not vary predictably with water temperature. The sampling of MPAs did not confound the resultant patterns. Instantaneous mortality rates were 0.245-0.685, highest at inner reefs and showed no consistent MPA-related patterns. Our study suggested that the mid and outer shelf waters of the GBR appeared best suited for growth of A. polyacanthus. In conclusion, position on continental shelves and related local environmental conditions needs to be considered in spatial models of growth.


1990 ◽  
Vol 41 (3) ◽  
pp. 399 ◽  
Author(s):  
MCL Dredge

Movement, growth and natural mortality rate of the red spot king prawn, Penaeus longistylus, occurring in waters of the Great Barrier Reef off Townsville, Queensland, were investigated in a series of tagging experiments. Adult P. longistylus did not migrate after leaving nursery areas. Their growth rate was slower than that of the conspecific species P. plebejus, and significant inter-annual variation in growth parameters was observed. The natural mortality rate, assessed by sequential tagging experiments that eliminated the possibility of confounding with the rate of fishing mortality, was estimated to be 0.072 (week-1).


1991 ◽  
Vol 42 (3) ◽  
pp. 241 ◽  
Author(s):  
RG Pearson ◽  
JL Munro

Growth, recruitment and mortality rates of a population of giant clams (Tridacna gigas and T. derasa) were monitored between 1978 and 1985 in a 2.7 ha study area on Michaelmas Reef, Great Barrier Reef. The initial 1978 census revealed the presence of 1166 T. gigas and 44 T. derasa. For T. gigas, the Fabens method provided growth-parameter estimates of L∞ = 85.7 cm, K = 0.07 and to = 0.732 year. The generated von Bertalanffy growth curve was a relatively poor fit to an empirical growth curve. A better description of growth was obtained for younger clams by using a forced value of L∞, = 80 cm, yielding K = 0.105 and to = 0.145 year. There was marked variability in the growth rate of individual clams, which has implications for the aquaculture industry. Average annual mortality rates in two census intervals (1978 to 1980-81 and 1980-81 to 1985) were 3.4 and 10.7% respectively. A comparison of the calculated size structure (assuming constant recruitment) with the observed size structure clearly suggested that recruitment was not constant and had declined drastically from a peak in the 1950s. For the much smaller population of T. derasa, the Fabens routine yielded estimates of L∞ = 46.91 cm, K= 0.108 and to = -0.188 year. The average annual mortality rate was 4.4%. Trends in recruitment could not be determined because of the small sample size. This study has highlighted the need for follow-up studies of this and other populations of giant clams if we are to understand more fully the processes of growth, recruitment and mortality in wild stocks and the implications for stock management and aquaculture.


2013 ◽  
Vol 93 (5) ◽  
pp. 1415-1421 ◽  
Author(s):  
Aymen Hadj Taieb ◽  
Mohamed Ghorbel ◽  
Nader Ben Hadj Hamida ◽  
Othman Jarboui

Samples of common two-banded seabream Diplodus vulgaris (N = 1097), used in this study, were caught in the Gulf of Gabès (Tunisia) from March 2008 to February 2010. Total length ranged from 7 to 25 cm. Diplodus vulgaris is a protandric hermaphrodite. The overall ratio of females to males was 1:1.66. The reproductive season extended from October to February, and the peak spawning activity occurred in December–January. The total length at which 50% of the population reached maturity was 14.14 ± 0.16 cm for females and 13.57 ± 0.01 cm for males. Parameters of the length–weight relationship (TW = aTLb) for all individuals were a = 0.0185 and b = 2.9319. The youngest specimen in this study was 0+ years, whereas the oldest one was 9 years. The von Bertalanffy growth parameters for the whole sample were: L∞ = 25.4 cm, k = 0.179 and t0 = −1.631 year. The instantaneous rate of natural mortality was: M = 0.333 year−1.


Diversity ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 67 ◽  
Author(s):  
Michael Kingsford ◽  
David Welch ◽  
Mark O’Callaghan

Patterns of age and growth of a sedentary damsel fish Acanthochromis polyacanthus were tested over a latitudinal range of approximately 10 degrees (1200 km) on the Great Barrier Reef (GBR), Australia. Within latitudes, these patterns were also compared on reefs in distance strata (inner, mid, and outer) across a continental shelf that ranged in width from 52 to 128 km. Although variation in length-max (SLMAX), growth, age-max (AMAX), and the von Bertalanffy metrics of Linf and K were found within and among latitudes, the greatest variation in some demographic characteristics was found among distance strata across the shelf regardless of latitude. Fish were always relatively smaller at inner shelf reefs and grew more slowly when compared to mid and outer shelf reefs; this was true regardless of the color morph of fish. The oldest fish collected was 11 years old, and there was no consistent variation in age-max among distances from shore. On outer reefs, there was a negative linear relationship with age-max and latitude. This “tropical gradient” of age only explained 34% of the variation; furthermore, this was not found when only the oldest group of fish was considered (top 10%). Fish only reached an age-max of six years on the southernmost reefs. There was a trend for a smaller Linf with latitude but it was not significant and Linf did not vary predictably with water temperature. The sampling of marine protected areas (MPAs) and fished zones did not confound the resultant patterns in that fish were not consistently larger or older in MPAs or fished zones. Instantaneous mortality rates were 0.245–0.685; they were highest at inner reefs and also showed no consistent MPA-related patterns. Our study suggested that the mid and outer shelf waters of the GBR appeared best suited for growth of A. polyacanthus. In conclusion, the position on continental shelves dominated other geographical patterns and needs to be considered in spatial models of growth. We suggest that local environmental conditions such as turbidity and the quality and quantity of plankton likely have a strong influence on distance across the shelf-based demographic patterns of planktivores.


Diversity ◽  
2017 ◽  
Vol 9 (1) ◽  
pp. 18 ◽  
Author(s):  
M. MacNeil ◽  
Karen Chong-Seng ◽  
Deborah Pratchett ◽  
Casssandra Thompson ◽  
Vanessa Messmer ◽  
...  

2016 ◽  
Vol 73 (10) ◽  
pp. 1575-1586 ◽  
Author(s):  
Allen H. Andrews ◽  
Edward E. DeMartini ◽  
Jeff A. Eble ◽  
Brett M. Taylor ◽  
Dong Chun Lou ◽  
...  

Bluespine unicornfish (Naso unicornis) from Hawaii were aged to >50 years using cross-sectioned sagittal otoliths. Fish length was a poor indicator of age because of rapid and variable early growth, exemplified by fish aged to be 4 years near maximum length. Growth was deterministic with adult ages decoupled from body length. Otolith mass and thickness were evaluated as proxies for age and both were encouraging; thickness explained more variance but mass was easier to measure. An age estimation protocol was validated through ontogeny using bomb radiocarbon (14C) dating. Use of the postbomb 14C decline period from a regional reference chronology enabled age validation of young fish — a novel approach for the Pacific Ocean. A probabilistic procedure for assigning bomb 14C dates (CALIBomb) was used for the first time to determine fish birth years. The age-reading protocol was generally validated, and it was possible to describe length-at-age despite difficulties in counting otolith annuli beyond 30–40 years. Growth curves differed between the sexes, and a four-parameter generalized von Bertalanffy growth function provided the best fit.


1992 ◽  
Vol 43 (5) ◽  
pp. 1301 ◽  
Author(s):  
BP Ferrira ◽  
GR Russ

Age and growth of the inshore coral trout P. maculatus from the central Great Barrier Reef region was determined by studies of annuli in whole and sectioned sagittae. The periodicity of formation of the annulus was validated through tetracycline labelling of mark-recaptured fishes in the wild and of captive fishes in aquaria. Results obtained from three recaptured and five captive fishes showed that annuli are formed once a year during late winter and spring months. von Bertalanffy growth-curve parameters were L∞ = 60.00 cm SL, K= 0.206 and to = - 0.945 year. The oldest specimen examined was a 12-year-old male of 58 cm SL. The total rate of mortality (Z) was estimated to be 0.569.


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