scholarly journals Age, growth and genetic status of the white shark (Carcharodon carcharias) from Kashima-nada, Japan

2011 ◽  
Vol 62 (6) ◽  
pp. 548 ◽  
Author(s):  
S. Tanaka ◽  
T. Kitamura ◽  
T. Mochizuki ◽  
K. Kofuji
Keyword(s):  
South Africa ◽  
Life History ◽  
Life History Traits ◽  
Growth Parameters ◽  
White Shark ◽  
Von Bertalanffy ◽  
Top Predator ◽  
Monophyletic Clade ◽  
Loop Region ◽  
D Loop

The white shark, a top predator inhabiting the world’s oceans, is an endangered species. However, knowledge of its life-history traits and population structure is still limited. We hypothesised that life-history traits would vary among populations because the species’ various habitats are diverse and change through time. Age was estimated by counting growth bands in the centra of white sharks caught in Japan. The von Bertalanffy growth parameters were estimated at L∞ = 455 cm TL, k = 0.196 year–1 and t0 = –1.92 years for males and L∞ = 607 cm TL, k = 0.159 year–1 and t0 = –1.80 years for females. The growth rate to maturity was higher than that known for individuals from California and South Africa. Male sharks matured at 310 cm TL at 4 years of age and females began to mature at ~450 cm TL and 7 years. The D-loop-region sequences of mitochondrial DNA extracted from Japanese white sharks and GenBank datasets from sharks of California, Australia, New Zealand and South Africa indicate that Japanese white sharks form a monophyletic clade separate from the populations of other regions. The results suggest that unique life-history traits of Japanese white sharks may be caused by genetic differences.

scholarly journals Age estimation, growth and maturity of the European hake (Merluccius merluccius (Linnaeus, 1758)) from Iberian Atlantic waters

2003 ◽  
Vol 60 (5) ◽  
pp. 1086-1102 ◽  
Author(s):  
C Piñeiro ◽  
M Saínza
Keyword(s):  
Life History ◽  
Age Estimation ◽  
Growth Parameters ◽  
Grey Literature ◽  
Von Bertalanffy ◽  
Merluccius Merluccius ◽  
Consistent Manner ◽  
The Mean ◽  
First Maturity ◽  
European Hake

Abstract Difficulties in age estimation for hake (Merluccius merluccius) have hampered the assessment of stocks. Here, we describe new, agreed ageing criteria based on the interpretation of the pattern of otolith growth. Improved estimates of von Bertalanffy growth parameters, and new estimates of maturity ogive parameters and length–weight relationships for European hake from Iberian Atlantic waters are presented. The results came from a study carried out during 1996–1997 and provide the first published account of the main life history traits of Southern stock hake. von Bertalanffy growth parameters of males were L∞ = 70cm, K = 0.18 year−1, and t0=−0.97 year, and those of females were L∞ = 89cm, K = 0.13 year−1, and t0 = −1.15 year. Growth of sexes differed from age 3 onwards, with females being on average larger and heavier than males. The estimated total length (L, cm)–total weight (W, g) relationships were W=0.0132135L2.8134246 for males and W=0.0086471L2.942563 for females. Spawning took place from December to May with a peak in February. The mean length and age at first maturity were 32.8 cm at 2.5 years for males and 45 cm at 4.4 years for females. Application of new ageing criteria showed that otolith sections may be used to determine ages up to 5 years in a consistent manner. These results indicate that hake of the Southern stock grow at higher rates and mature earlier than previously considered. Summaries of hake's life history parameters from other marine regions are also presented in order to make information that belongs largely to the grey literature available.

Genetic variation of two species with different life-history traits in the endangered renosterveld of South Africa - a comparative analysis ofEriocephalus africanusandHemimeris racemosa

2015 ◽  
Vol 53 (4) ◽  
pp. 447-453 ◽  
Author(s):  
Steffen Heelemann ◽  
Veronika Bäuerlein ◽  
Cornelia B. Krug ◽  
Karen J. Esler ◽  
Peter Poschlod ◽  
...  
Keyword(s):  
South Africa ◽  
Genetic Variation ◽  
Life History ◽  
Comparative Analysis ◽  
Life History Traits

scholarly journals Environmentally Modulated Repeat Evolution of Polymorphic Arctic Charr Life History Traits

2021 ◽  
Vol 9 ◽  
Author(s):  
Gabrielle Grenier ◽  
Aslak Smalås ◽  
Runar Kjær ◽  
Rune Knudsen
Keyword(s):  
Life History ◽  
Life History Traits ◽  
Growth Parameters ◽  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Local Environment ◽  
Life History Strategies ◽  
Age At Maturity ◽  
First Time ◽  
Sympatric Morphs

Sympatric Arctic charr, Salvelinus alpinus (L. 1758), morphs have flexible but repeated life history strategies tested across five Norwegian lakes. In several Scandinavian polymorphic Arctic charr populations differentiated by their diet and habitat use, a large littoral omnivorous (LO) morph commonly cooccurs with a smaller profundal spawning (PB/PZ) morph. A third, large piscivorous (PP) morph is also known to occur within a portion of Arctic charr populations in the profundal habitat along with the PB/PZ individuals. Life history traits, such as age at maturity, growth, and diet are known to differ among coexisting morphs. Notably, the PP morph was the longest morph with the oldest age at maturity while the PB/PZ morph showed the shortest lengths overall and youngest age with LO morph being intermediate in both traits. Growth parameters differed across all the morphs. When examining growth within morph groups, the LO morph was found to have different growth across all lakes, while similar reproductive investments and different energy acquisition patterns were seen within the PB/PZ and PP morphs. These results suggest repeat evolution in several life history strategies of reproductively isolated Arctic charr sympatric morphs, notably for the first time in the PP morph, while also highlighting the importance of the local environment in modulating life history traits.

scholarly journals Life-history traits of the spiny dogfish Squalus acanthias in the Adriatic Sea

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Giada Bargione ◽  
Fortunata Donato ◽  
Mario La Mesa ◽  
Carlotta Mazzoldi ◽  
Emilio Riginella ◽  
...  
Keyword(s):  
Life History ◽  
Life History Traits ◽  
Adriatic Sea ◽  
Growth Parameters ◽  
Sampling Period ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
The North ◽  
Size At Sexual Maturity ◽  
The Individual

Abstract Pivotal life history traits concerning age structure and reproduction of the spiny dogfish (Squalus acanthias, Linnaeus 1758) were investigated in the Adriatic Sea from mid February 2012 to mid July 2013 and in 2016. The whole sample consisted of 176 females and 150 males, ranging between 217–1025 mm and 219–875 mm, respectively. The individual age, which was estimated using a cross-sectioning technique of the second dorsal-fin spine, ranged from 0 to 13+ years for females and from 0 to 9+ years for males. Based on the length-at-age estimates, the Gompertz growth parameters were L∞ = 1130 mm, k = 0.18 and L∞ = 920 mm, k = 0.24 for females and males, respectively. The size at sexual maturity (L50) was 659 mm for females and 575 mm for males, corresponding to 7.5 and 5.5 years of age (A50), respectively. Mean biennial fecundity was approximately 11 embryos/female and 12 ripe oocytes/female. Mature males occurred during much of the sampling period, while mature females with nearly full-term embryos were exclusively recorded in May 2013 and July 2016. Monitoring of catches conducted in a sample port of the north Adriatic (Chioggia) over the past 20 years has shown fluctuating trends in landings, with peaks during the summer reproductive season.

scholarly journals Louse (Insecta: Phthiraptera) infestations of the Amur Falcon (Falco amurensis) and the Red-footed Falcon

2015 ◽  
Vol 23 (1) ◽  
pp. 58-65 ◽  
Author(s):  
Imre Sándor Piross ◽  
Péter Fehérvári ◽  
Zoltán Vas ◽  
Szabolcs Solt ◽  
Éva Horváth ◽  
...  
Keyword(s):  
South Africa ◽  
Life History ◽  
Host Species ◽  
Life History Traits ◽  
Population Parameters ◽  
Model Species ◽  
Host Parasite Interactions ◽  
Louse Species ◽  
Host Parasite ◽  
First Time

Abstract Little is known about the louse species harboured by Red-footed and Amur Falcons despite the fact that various life-history traits of these hosts make them good model species to study host-parasite interactions. We collected lice samples from fully grown Amur (n=20) and Red-footed Falcons (n=59), and from nestlings of Red-footed Falcons (n=179) in four countries: Hungary, India, Italy and South Africa. We identified 3 louse species on both host species, namely Degeeriella rufa, Colpocephalum subzerafae and Laembothrion tinnunculi. The latter species has never been found on these hosts. Comparing population parameters of lice between hosts we found significantly higher prevalence levels of D. rufa and C. subzerafae on Amur Falcons. Adult Red-footed Falcons had higher D. rufa prevalence compared to C. subzerafae. For the first time we also show inter-annual shift in prevalence and intensity levels of these species on Red-footed Falcons; in 2012 on adult hosts C. subzerafae had higher intensity levels than D. rufa, however in 2014 D. rufa had significantly higher intensity compared to C. subzerafae. In case of nestlings both louse species had significantly higher preva lence levels than in 2014. The exact causes of such inter-annual shifts are yet to be understood.

Life history traits of the exploited limpet Patella candei (Mollusca: Patellogastropoda) of the north-eastern Atlantic

2011 ◽  
Vol 92 (6) ◽  
pp. 1379-1387 ◽  
Author(s):  
P. Henriques ◽  
R. Sousa ◽  
A.R. Pinto ◽  
J. Delgado ◽  
G. Faria ◽  
...  
Keyword(s):  
Life History ◽  
Mortality Rate ◽  
Sexual Maturity ◽  
Life History Traits ◽  
Growth Parameters ◽  
Total Mortality ◽  
Recruitment Pattern ◽  
Length Relationship ◽  
North Eastern ◽  
Exploitation Rate

Life history traits of Patella candei were studied for the first time, including weight versus length relationship, growth, age structure, sexual maturity, recruitment pattern, mortality rates and yield and biomass-per-recruit of an exploited population in Madeira Island, north-eastern Atlantic using monthly length–frequency data from January to December 1999. The growth pattern of P. candei showed positive allometric nature of growth (b > 3, P < 0.05). The estimated growth parameters showed an asymptotic length (L∞) and growth coefficient (K) estimated at 80.81 mm and K at 0.32 year−1 with a growth performance index (φ′) calculated as 3.32 based on the collected data. This species is moderately long-lived reaching up to 9.36 years and achieving sexual maturity at 36.7 mm of shell length. The recruitment pattern was continuous, displaying a major peak event per year, occurring in January (25.12%). The estimated total mortality rate (Z) was 1.79 year−1 while natural mortality rate (M) was 0.55 year−1 and fishing mortality rate (F) was 1.24 year−1. The probability of capture shows that the length at first capture (Lc) was 42.7 mm, the exploitation rate (E) 0.693 and the maximum allowable limit of exploitation (Emax) was 0.779 for the highest yield. The exploitation rate was less than the predicted Emax values, showing that the stock of P. candei was found to be under-exploited in the investigated area; however, its slow growth and long life make it extremely vulnerable to over-exploitation.

scholarly journals Possible causes of a substantial decline in sightings in South Africa of an ecologically important apex predator, the white shark

2021 ◽  
Vol 117 (1/2) ◽  
Author(s):  
Robin Fisher
Keyword(s):  
South Africa ◽  
White Shark ◽  
Direct And Indirect Effects ◽  
Apex Predator ◽  
Top Predator ◽  
Causative Factors ◽  
Kwazulu Natal ◽  
Galeorhinus Galeus ◽  
Substantial Decline ◽  
Ecosystem Changes

A decline in sightings of a top predator, the white shark (Carcharadon carcharias), in South Africa was quantified in order to identify possible causes for this decline. White shark sightings data across 8 years (2011–2018), recorded from a cage-diving vessel in Gansbaai are reported. A significant decline in mean total white shark sightings per boat trip (>6 in 2011 to <1 in 2018) and a 69% reduction in the probability of a sighting were found. Correlating with this decline in sightings is a rise in sightings of sevengill sharks (Notorynchus cepedianus) in False Bay and copper sharks (Carcharhinus brachyurus) in Gansbaai, as well as substantial ecosystem changes. The effects of lethal conservation measures such as the use of shark nets in KwaZulu-Natal; the direct and indirect effects of overfishing including a reduction in smoothhound (Mustelus mustelus) and soupfin (Galeorhinus galeus) sharks; and novel predation on white sharks are discussed as possible causative factors for this decline in white shark sightings.

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