Larval Flatfish Distributions and Drift on the Southern Grand Bank

1992 ◽  
Vol 49 (3) ◽  
pp. 467-483 ◽  
Author(s):  
Kenneth T. Frank ◽  
John W. Loder ◽  
James E. Carscadden ◽  
William C Leggett ◽  
Christopher T. Taggart
Keyword(s):  
Growth Rate ◽  
Thermocline Depth ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Yellowtail Flounder ◽  
Limanda Ferruginea ◽  
Larval Drift ◽  
Vertical Distributions ◽  
Hippoglossoides Platessoides ◽  
Rule Out

Ichthyoplankton and hydrographic surveys of the southern Grand Bank in September of 1986, 1987, and 1988 revealed substantial correspondence between the areal distributions of larvae of three flatfish species and temperature below the thermocline. Depth-averaged densities of American plaice (Hippoglossoides platessoides) were negatively correlated with temperature whereas yellowtail flounder (Limanda ferruginea) and witch flounder (Glyptocephalus cynoghssus) densities were positively correlated with temperature. In spite of large interannual differences in abundance, the larval distributions showed similar structure from year to year. Using estimates of larval age inferred from length frequency distributions and literature values for growth rate, in conjunction with moored current measurements, estimates of spawning times and locations were obtained for each species. These estimates were compared with historical information on the distribution of prespawning fish for each species to examine the hypothesis of passive larval drift. The results indicate that in most, but not all cases, the larval distributions and currents are consistent with passive larval drift for particular growth rates and vertical distributions. However, the observations are not adequate to rule out alternative mechanisms involving behaviour.

Studies on southern Australian Abalone (Genus Haliotis). VIII. Growth of juvenile H. laevigata

1988 ◽  
Vol 39 (2) ◽  
pp. 177 ◽  
Author(s):  
SA Shepherd
Keyword(s):  
Growth Rate ◽  
South Australia ◽  
Length Frequency ◽  
Frequency Distributions ◽  
The Mean

The growth of juvenile H. laevigata was studied by analysis of sequences of length-frequency distributions obtained in below- and above-boulder habitats at West Island, South Australia. The mean growth rate overall is 1.69 mm month-1 and is linear with length for the first 5 years, but thereafter declines with increasing length. The mean growth rate of four groups of marked H. laevigata aged 1 and 3 years is 1.6-2.1 mm month-1, and thus supports the estimation of growth rate from analysis of length-frequency distributions.

Reference points for the length-based indicator Lmax5% for use in the assessment of data-limited stocks

2019 ◽  
Vol 76 (7) ◽  
pp. 2125-2139 ◽  
Author(s):  
Tanja Miethe ◽  
Yves Reecht ◽  
Helen Dobby
Keyword(s):  
Life Histories ◽  
Stock Assessment ◽  
Reference Points ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Simulation Tools ◽  
Spawning Potential Ratio ◽  
The Mean ◽  
Commercial Sources ◽  
Length Frequency Data

Abstract In the absence of abundance indices from scientific surveys or commercial sources, reliable length frequency data from sampled commercial catches can be used to provide an indirect assessment of fishing mortality. Length-based indicators are simple metrics which describe length frequency distributions. The length-based indicator Lmax5%, the mean length of the largest 5% of individuals in the catch, combined with appropriately selected reference points, can be used to evaluate the presence of very large individuals in the catch and hence determine exploitation level. Using analytical per-recruit models, we derive reference points consistent with a spawning potential ratio of 40%. The reference points depend on the life history parameters for natural mortality, maturity, and growth (M, Lmat, L∞, k, CVL∞). Using available simulation tools, we investigate the sensitivity of the reference points to errors in these parameters and explore the usefulness of particular reference points for management purposes for stocks with different life histories. The proposed reference points are robust to uncertainty in length at first capture, Lc, and take into account the maturation schedule of a species. For those stocks with high M/k ratios (>1), Lmax5%, combined with the appropriate reference point, can be used to provide a data-limited stock assessment.

Size Distributions and Growth of the Fan-shell Pinna bicolor Gmelin (Mollusca : Eulamellibranchia) in South Australia

1979 ◽  
Vol 30 (1) ◽  
pp. 25 ◽  
Author(s):  
AJ Butler ◽  
FJ Brewster
Keyword(s):  
South Australia ◽  
Adductor Muscle ◽  
Size Distributions ◽  
Limited Data ◽  
Length Frequency ◽  
Age Classes ◽  
Frequency Distributions ◽  
Growth And Survival ◽  
Random Samples ◽  
Variable Success

Fourteen random samples of Pinna bicolor were collected over a period of 31 months from 6 m depth in Gulf St Vincent off Edithburgh, South Australia. The length-frequency distributions suggest that: P. bicolor larvae settle in spring but with variable success; growth of newly settled young is rapid over summer; by age 1 year their modal shell length is about 20 cm; by age 2 it is about 26 cm; they may survive substantially longer than 3 years so that a length-class of mode c. 35 cm is always present and is composed of several age-classes not necessarily equally represented. These suggestions are corroborated by limited data on adductor muscle scars, the development of epibiota on the shells, and the growth and survival of tagged animals over 9 months.

Application of the otolith weight – age relationship for the pilchard, Sardinops sagax neopilchardus

1995 ◽  
Vol 52 (4) ◽  
pp. 657-664 ◽  
Author(s):  
W. J. Fletcher
Keyword(s):  
Maximum Size ◽  
Steady Increase ◽  
Average Weight ◽  
Fish Length ◽  
Natural Mortality ◽  
Length Frequency ◽  
Age Classes ◽  
Frequency Distributions ◽  
Southwestern Australia ◽  
Sardinops Sagax

Adult pilchard (Sardinops sagax neopilchardus) from southwestern Australia held in fish cages for 1 year showed minimal increase in mean length but a steady increase in mean otolith weight (1.61–1.83 mg); this increase (0.22 mg) closely parallels the previously calculated mean difference between adjacent age classes (0.24 mg). Modes in otolith weight frequency distributions of fishery-caught pilchards, previously suggested as corresponding with separate year classes, generally persisted and progressed through subsequent samples. By contrast, fish length frequency distributions of these samples showed no consistent modal progression. The average weight of otoliths for year classes 2–8 were used to calculate growth rates: following sexual maturity, at age 2, males grew to a significantly smaller maximum size than females (L∞ = 162 and 172 mm respectively). The otolith weight – age relationship, validated by following a cohort of unusually low abundance as it moved through the fishery, indicated that recruitment to the fishery generally began at age 2 but was not complete until age 4. These data have been successfully used in forecasting the catch rate of the fishery up to 2 years in advance and providing an estimate of the rate for natural mortality of 0.43.

Age, stucture, growth rates and movements of sea mullet, Mugil cephalus L., and Yellow-eye Mullet, Aldrichetta forsteri (Valenciennes), in the Swan-Avon river system, Western Australia

1981 ◽  
Vol 32 (4) ◽  
pp. 605 ◽  
Author(s):  
CF Chubb ◽  
IC Potter ◽  
CJ Grant ◽  
RCJ Lenanton ◽  
J Wallace
Keyword(s):  
Growth Rates ◽  
River System ◽  
First Year ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Using Data ◽  
The Times ◽  
First Year Of Life ◽  
Breeding Seasons ◽  
System 1

The age structure, growth rates and movements of M. cephalus and A forsteri in the Swan-Avon river system have been investigated using data obtained from beach seining and gill netting carried out between February 1977 and June 1980. Length-frequency data and scale readings show that the populations of both species consist predominantly of 0+ and 1 + fish. From the times when the smallest fry (20-30 mm) were present in the lower part of the river system, and from the condition of the gonads of older fish, the breeding seasons of the sea and yellow-eye mullets have been estimated as extending from March to September and from March to August respectively. The bimodality or polymodality exhibited by the length-frequency distributions for the 0 + year classes suggest that in both species groups of individuals spawn at slightly different times. The range of mean total lengths and weights of animals caught in May near the end of the first year of life was 178-222 mm and 64-119 gin M. cephalus and 136-154 mm and 19-30 g in A. forsteri, which shows that the growth of each of these two species of mullet is relatively very rapid in the Swan-Avon river system. 1 + and 2 + fish tend to leave the estuary for varying periods. Although 0+ fish of both species utilized the shallow banks of the estuary throughout the year. the sea mullet moved further upstream and were not as consistently abundant in the lower estuary. Since 0+ yellow-eye mullet 40-100 mm long were also abundant in marine coastal waters between January and May. and sea mullet of comparable age were rarely observed in these regions, it would appear that M. cephalus is the more estuarine-dependent of the two species. Commercial catches of M. cephalus were greater than those of A. forsteri. This feature can be related in part to the much faster growth rate of M. cephalus, which results in a larger proportion of its youngest year classes reaching the minimum legal size for capture prior to the time when they leave the estuary in large numbers.

The Future of the Nigerian Agricultural Industries: A Case Study of Oil Palm Production in Edo State

2013 ◽  
Vol 824 ◽  
pp. 561-567 ◽  
Author(s):  
U.J. Udosen ◽  
A.P. Ugboya
Keyword(s):  
Growth Rate ◽  
Oil Palm ◽  
Frequency Distributions ◽  
Factors Influencing ◽  
The Future ◽  
Edo State ◽  
Agricultural Industries ◽  
Fresh Fruit Bunches ◽  
Planting Materials

This study analyzes oil palm production from 2001 - 2008 in Edo State, with a view of establishing the future of Nigerian Agricultural oil palm industries. The specific objectives were to identify and quantify the factors influencing the production of oil palm, reveal the constraints to the production of oil palm; analyze the viability of oil palm production as an investment and predict the future of oil palm enterprise in Edo State. Three Local Government Areas of high oil palm concentration in Edo State were covered. Ninety selected oil palm producers from nine villages in the study area were selected. Frequency distributions and multiple regression analysis were used to analyze the results. The results showed that for the period under review (2001 - 2008) on a per hectare basis, seedlings cost, and labour cost were significant inputs, positively influencing the production of oil palm in the Edo State. A growth rate of 6.2% and 23.5% were projected for oil palm with reference to palm oil and fresh fruit bunches (FFB), respectively, up to the year 2020, an indication that oil palm production in the State is viable and the future is bright. The study revealed that inadequate storage facilities, poor planting materials and lack of government assistance, among others, are major bottlenecks in oil palm production in Edo State. However, since oil palm production in Edo State is viable, it is an indication that the future of Nigerian Agricultural Industries is bright.

scholarly journals Age, growth, and recruitment patterns of juvenile ladyfish (Elopssp) from the east coast of Florida (USA)

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1392
Author(s):  
Juan C. Levesque
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Age And Growth ◽  
Growth Equation ◽  
Length Frequency ◽  
Daily Growth ◽  
Exponential Regression ◽  
Absolute Growth ◽  
Specific Growth Rates ◽  
Size At Age

Ladyfish (Elopssp) are a common and economically valuable coastal nearshore species found along coastal beaches, bays, and estuaries of the southeastern United States, and subtropical and tropical regions worldwide. Previously, ladyfish were a substantial bycatch in Florida’s commercial fisheries, but changes in regulations significantly reduced commercial landings. Today, ladyfish are still taken in commercial fisheries in Florida, but many are also taken by recreational anglers. Life-history information and research interest in ladyfish is almost non-existent, especially information on age and growth. Thus, the overarching purpose of this study was to expand our understanding of ladyfish age and growth characteristics. The specific objectives were to describe, for the first time, age, growth, and recruitment patterns of juvenile ladyfish from the east coast of Florida (USA). In the Indian River Lagoon (IRL), annual monthly length-frequency distributions were confounded because a few small individuals recruited throughout the year; monthly length-frequency data generally demonstrated a cyclical pattern. The smallest were collected in September and the largest in May. Post-hoc analysis showed no significant difference in length between August and May, or among the other months. In Volusia County (VC), annual monthly length-frequency distribution demonstrated growth generally occurred from late-winter and spring to summer. The smallest ladyfish were collected in February and the largest in August. On average, the absolute growth rate in the IRL was 36.3 mm in 60 days or 0.605 mm day−1. Cohort-specific daily growth rates, elevations, and coincidentals were similar among sampling years. Cohort-specific growth rates ranged from 1.807 in 1993 to 1.811 mm day−1in 1994. Overall, growth was best (i.e., goodness of fit) described by exponential regression. On average, the absolute growth rate in VC was 28 mm in 150 days or 0.1866 mm day−1. Cohort-specific daily growth rates were significantly different among sampling years; however, the elevations and coincidentals were similar. Cohort-specific growth rates ranged from 1.741 in 1994 to 1.933 mm day−1in 1993. Mean ladyfish growth was best described by linear regression; however, natural growth was explained better by exponential regression. In the IRL, the corrected exponential growth equation yielded a size-at-age 1 of 156.0 mm SL, which corresponded to an estimated growth rate of 0.4356 mm day−1. In VC, the corrected exponential growth equation yielded a size-at-age 1 of 80 mm SL corresponding to an estimated growth rate of 0.2361 mm day−1.

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