Density Dependence of Larval Growth of a Marine Fish, the Southern Bluefin Tuna, Thunnus maccoyii

1991 ◽  
Vol 48 (8) ◽  
pp. 1358-1363 ◽  
Author(s):  
Greg P. Jenkins ◽  
Jock W. Young ◽  
Tim L. O. Davis
Keyword(s):  
Growth Rate ◽  
Marine Fish ◽  
Food Limitation ◽  
Larval Growth ◽  
Bluefin Tuna ◽  
Density Dependent ◽  
East Indian ◽  
Southern Bluefin Tuna ◽  
Slow Growing ◽  
East Indian Ocean

Competition for food among larvae and subsequent reduction in growth rates has been proposed as a mechanism to explain the apparent density-dependent control of some exploited marine fish populations, but has received little support from field data. Growth of larvae of southern bluefin tuna, Thunnus maccoyii, in the East Indian Ocean was significantly different among stations sampled randomly within a 20-km radius. Growth rate was positively correlated with feeding rate but not with temperature, indicating that larvae were food limited to a varying degree. A negative correlation between growth rate and abundance suggested that food limitation was density dependent. Regression analysis indicated that in areas of highest larval densities there was an approximate 25% reduction in growth rate. We suggest that in areas of high abundance, larvae were competing for food, leading to a density-dependent reduction of growth rate. Because the larval stage of high mortality is prolonged, cumulative mortality of slow-growing larvae over this period may be greater, even if the mortality rate is constant.

The effect of food level on growth rate and frequency of metamorphosis and paedomorphosis in Ambystoma gracile

1992 ◽  
Vol 70 (1) ◽  
pp. 87-93 ◽  
Author(s):  
Lawrence E. Licht
Keyword(s):  
Growth Rate ◽  
Growth Response ◽  
Larval Growth ◽  
Food Level ◽  
Factors Influencing ◽  
Size At Metamorphosis ◽  
Effect Of Food ◽  
Food Body ◽  
Life History Patterns ◽  
Slow Growing

The effect of food level on larval growth response and frequency of metamorphosis and paedomorphosis was examined in Ambystoma gracile from high- and low-elevation populations in British Columbia. Larvae that eventually metamorphosed and those that became paedomorphic did not differ in growth rates when fed equal quantities of food. Body size at metamorphosis did not differ between fast- and slow-growing larvae, but larvae fed high levels of food metamorphosed sooner than those fed less. Food level had no effect on the frequency of metamorphosis and paedomorphosis. Larvae of different sexes did not differ in growth rate or frequency of metamorphosis and paedomorphosis, nor did larvae originating from populations from high and low elevations. Variation in the metamorphic response occurred within and between larvae from separate egg clutches. The findings are discussed in light of current hypotheses on factors influencing alternative life-history patterns in facultatively paedomorphic salamanders.

scholarly journals TINGKAT EKSPLOITASI IKAN TUNA SIRIP BIRU SELATAN (Thunnus maccoyii) DI SAMUDERA HINDIA BERDASARKAN HASIL TANGKAPAN YANG DIDARATKAN DI PELABUHAN BENOA, BALI

2016 ◽  
Vol 5 (4) ◽  
pp. 345-352
Author(s):  
Damar Nusawicaksono Kurniawan ◽  
Abdul Ghofar ◽  
Suradi Wijaya Saputra ◽  
Bram Setyadji
Keyword(s):  
Growth Rate ◽  
Size Structure ◽  
Stock Assessment ◽  
Total Mortality ◽  
Bluefin Tuna ◽  
Fisheries Resources ◽  
Southern Bluefin Tuna ◽  
The Indian Ocean ◽  
Data Length ◽  
Length Frequency Data

ABSTRAK Pengkajian dan pendugaan status sumberdaya perikanan di suatu wilayah perairan dapat dilakukan dengan mengetahui laju eksploitasinya. Data frekuensi panjang merupakan salah satu data yang dapat digunakan untuk melakukan pendugaan tingkat eksploitasi tersebut. Penelitian ini bertujuan untuk menduga nilai mortalitas, laju pertumbuhan, ukuran pertama kali tertangkap dan tingkat eksploitasi. Penelitian dilakukan pada bulan April-Mei 2016 di Loka Penelitian Perikanan Tuna Pelabuhan Benoa, Denpasar, Bali. Metode yang digunakan adalah metode survei. Sementara data panjang ikan tuna sirip biru selatan tahun 2013-2014 kemudian diolah dengan perangkat lunak FISAT II. Hasil penelitian menunjukkan struktur ukuran ikan tuna sirip biru selatan 145 - 210 cmFL dengan modus di ukuran 170-174 cmFL, ukuran pertama kali tertangkap (Lc) 171 cmFL, hubungan panjang berat mendapat nilai W= 0,00006*FL2,792, faktor kondisi berada pada angka 1,86-2,00, laju pertumbuhan yang didapat yaitu Lt=220,50(1 - e 0,2(t+0,488)), dimana nilai dari L∞ yaitu 220,50 cmFL dan nilai t0 -0,49, laju mortalitas total (Z) sebesar 1,14/tahun, laju mortalitas alami (M) sebesar 0,36/tahun, dan laju mortalitas akibat penangkapan (F) sebesar 0,78/tahun, dan tingkat eksploitasi (E) 0,68/tahun, Hal ini menunjukan penangkapan  ikan tuna sirip biru selatan oleh kapal rawai tuna di Samudera Hindia dalam keadaan berlebih (overfishing) karena nilai tingkat eksploitasi yang didapat melebihi tingkat pemanfaatan optimum atau Eopt = 0,5/tahun (0,68 > 0,5). Kata Kunci : Ikan Tuna Sirip Biru Selatan, Tingkat Eksploitasi, Mortalitas, Pertumbuhan  ABSTRACT Stock assessment and prediction status of fisheries resources in the waters can be made by knowing the rate of exploitation. Length-frequency data is one can be used to suspect rate of exploitation . The aimed of this research was to suspect value of mortality, the growth rate, size at first capture and the level of exploitation. This research was conducted on April-May 2016 at the Loka Fishery Tuna's Research Benoa Port, Denpasar, Bali. This research used survey method.While data length of the southern bluefin tuna 2013-2014 was processed with FISAT II. The results showed size structure of southern bluefin tuna 145-210 cmFL with mode in sizes 170-174 cmFL, size at first capture (Lc) 171 cmFL, value of lenght and weight relationship W = 0,00006 *,792 FL2, condition factors 1,86-2.00, the growth rate Lt = 220,50 (1-e of 0.2 (t + 0,488)), where the value of L ∞ was 220.50 cmFL and value t0 -0.49 total mortality rate (Z) of 1.14/year, rate of natural mortality (M) of 0.36/year, and  rate of mortality due to the arrest of (F) amounted to 0.78/year, and the rate of exploitation (E) 0,68/year, it shows the fishing of southern bluefin tuna by the longline in the Indian Ocean was overfishing because level of exploitation value was over the optimum effort or Eopt = 0,5/year (0.68 > 0.5). Keyword: Southern Bluefin Tuna, exploitation rate, Mortality, growth,

Southern bluefin tuna populations in south-west Australia

1965 ◽  
Vol 16 (1) ◽  
pp. 25 ◽  
Author(s):  
JS Hynd
Keyword(s):  
Growth Rate ◽  
Age Groups ◽  
Bluefin Tuna ◽  
Length Frequency ◽  
South West ◽  
Size Groups ◽  
Southern Bluefin Tuna ◽  
The Times

Length-frequency histograms of southern bluefin tuna caught for tagging and other purposes by F.V. Estelle Star in the course of survey operations showed heterogeneity in that the catches contained size groups, the differences between which could not be regarded as simply those to be expected between the age groups of a single stock. The times at which these groups appeared in the catches showed that the groups were characterized by distinct distributional behaviour, and this was confirmed by the results of the tagging operations. However, the groups are indistinguishable in their growth rate, so far as this has been shown by the present work, and no evidence is yet available as to the origins or status of these groups.

Influence of food availability, predation risk and initial body size on growth and maturation of Cloeon dipterum (Ephemeroptera: Baetidae)

Zoosymposia ◽  
2016 ◽  
Vol 11 ◽  
pp. 53-64 ◽  
Author(s):  
JAN ŠUPINA ◽  
JINDŘIŠKA BOJKOVÁ ◽  
DAVID S. BOUKAL
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Body Size ◽  
Predation Risk ◽  
Food Availability ◽  
Larval Mortality ◽  
Food Limitation ◽  
Larval Growth ◽  
Influence Of Food ◽  
Cloeon Dipterum

Larval growth and maturation in aquatic insects are phenotypically plastic and can change in response to the amount and quality of resources, or under predation risk. While better food conditions typically lead to faster growth and earlier maturation at larger body size and hence higher fecundity, the effects of predation risk can vary depending on its strength and selectivity with respect to size or stage. Studies on lotic mayflies (Ephemeroptera) have reported two direct and two indirect life history responses to increased predation risk: slower growth rate and later maturation at the same or smaller size, and faster or unaltered growth rate and earlier maturation at smaller body size. However, life history responses of standing water mayflies to predation risk are unknown. To fill this gap, we carried out a full-factorial laboratory experiment to study the influence of food availability (full/reduced) and predation risk (present/absent predator cues) by dragonfly larvae on growth and maturation of larvae of the lentic mayfly Cloeon dipterum. Males and females responded similarly to food limitation and predation risk. Predation risk had no effect on maturation size, larval mortality and metamorphic failure. However, growth rate, number of moults and development time were all affected by predation risk, and its net effect was modified by food availability and initial body size of the larvae. These results suggest that life history responses to suboptimal conditions depend on body size at the onset of such conditions. Finally, a small group of larvae grew at much slower rates and developed much longer than other individuals of similar initial size, possibly due to bet-hedging or inclusion of multiple genotypes in the experiment.

The Southern Bluefin Tuna, Thunnus thynnus maccoyii (Castelnau), in Australian Waters

1956 ◽  
Vol 7 (1) ◽  
pp. 1 ◽  
Author(s):  
DL Serventy
Keyword(s):  
Growth Rate ◽  
Feeding Habits ◽  
Bluefin Tuna ◽  
Thunnus Thynnus ◽  
Younger Age ◽  
Southern Bluefin Tuna ◽  
Local Breeding ◽  
Australian Coastline ◽  
Migratory Movements ◽  
Length Frequency Data

This paper deals with the results of the investigations of the Division of Fisheries, C.S.I.R.O., into the biology of the southern bluefin tuna (Thunnus thynnus maccoyii (Castelnau)), a representative in southern Australia and New Zealand of the tunny of Europe and the bluefin tuna of California. A comparative description of the morphology of the ,Australian form is given with a detailed study of its occurrence in Australia, including a discussion of the possible presence of local breeding stocks. The growth rate is considered from a study of length frequency data.' Considerable variations have been found in the growth rate of the younger age classes, as well as fluctuations in their relative abundance and their migratory movements along the eastern Australian coastline. Reference is made to the feeding habits in various areas.

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