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1.
Reproductive biology and growth of bluestripe herring Herklotsichthys quadrimaculatus (Rüppell, 1837) in the northernmost waters 下载免费PDF全文
In order to examine the reproductive biology and growth of Herklotsichthys quadrimaculatus in the northernmost part of its reproductive range, the size frequency, gonadal development, and otolith daily increments of this species were collected from the coastal waters of Okinawa Island, southern Japan. Juveniles (<25 mm standard length, SL) were found from April to August. Their size increased to ca. 100 mm SL in November and subsequently remained unchanged. The gonadosomatic index of females was higher (>3.0) between March and August, which was the estimated spawning period. The modal hatching period back‐calculated from otolith daily increments was from April to May, which would be the peak of spawning. Because mature and spent ovaries also contained mature and immature oocytes, it was concluded that females spawn several times during the spawning season. Age determination from otolith increments showed logistic growth up to 97 mm (ca. 180 days post‐hatch), after which growth was almost stagnant. Maximum size and age were 121.6 mm SL and 384 days, respectively. The adult size decreased between August and September, indicating a change in the age cohort. Thus, the fish reached the end of their lifespans after spawning. Some of these ecological features were different from those of a previous study performed in southern areas; these differences suggest a flexible life history that could change to adapt to the surrounding environment. 相似文献
2.
The objective of this study was to determine the basic population‐specific parameters necessary for fish stock assessment in the area and to compare these with data from other Mediterranean regions. White seabream Diplodus sargus sargus (n = 449) were caught along the Algerian coast between December 2005 and December 2006. Total length ranged from 12.2 to 34.6 cm, representing age classes between 0 and 10 years. Validity of the otolith readings for estimating age and growth was supported using the back‐calculation method. The von Bertalanffy growth parameters for all fish were calculated as: TL = 36.3 cm, k = 0.154 year−1, t0 = −0.488 year. The growth performance index (φ) showed a relatively slow growth of the local population. The length‐weight relationship showed an isometric growth (b = 2.98; r = 0.98). Subspecies Diplodus sargus sargus was characterized as being a proterandric hermaphrodite. Overall ratio of males to females was 1 : 1.4, with males predominant in the smaller size intervals and females in the larger ones. The reproductive season extended from January to May, with a March–April peak in spawning activity. Fifty per cent maturity of the tested cohort was reached at a total length of 20.2 cm for males and 20.0 cm for females. 相似文献
3.
Patrick M. Graham James S. Franks Evan J. Anderson Robert T. Leaf Jason D. Tilley 《Journal of fish biology》2021,99(4):1190-1200
Age and growth of early-life-stage Atlantic tarpon Megalops atlanticus collected from Mississippi coastal waters in the northcentral Gulf of Mexico (GOM) are described using otolith microstructure analysis. Tarpon leptocephali (n = 95, 16.0—27.8 mm standard length, LS) collected from June throughOctober 2013—2018, ranged in age from 22 to 43 days (mean = 30.9 ± 0.5 days). Leptocephalus somatic growth rates ranged 0.46—1.24 mm day−1 (mean = 0.76 ± 0.02 mm day−1), and leptocephalus otolith growth rates ranged 1.78—3.97 μm day−1 (mean = 2.58 ± 0.04 μm day−1). Growth rates were inversely correlated to leptocephalus age, indicating the shrinkage phase associated with leptocephalus metamorphosis. Juvenile tarpon (n = 358, 50—359 mm fork length, LF) were collected from August through December 2007—2018. Juveniles exhibited a positive allometric relationship (adjusted R2 = 0.99, P < 0.001) between length and mass. The age of 100 juveniles (71—277 mm LF) ranged from 76 to 174 days. Juvenile growth rate was estimated as 1.56 ± 0.11 mm day−1. Significant (P < 0.001) linear relationships were found between juvenile age and otolith metrics, including otolith mass (R2 = 0.81) and radius (R2 = 0.68). Evaluation of the backcalculated hatch dates suggests that specimens in the collection hatched from late May through mid-September with slight peaks during July and August. A Rao's Spacing Test of Uniformity indicates the presence of significant lunar periodicity in leptocephalus hatch dates (n = 95, U = 250.1, P < 0.05), with 50% of the leptocephali hatched within 5 days (before or after) of the full moon. This study fills critical gaps in the scientific knowledge of tarpon and provides estimates of early-life-history metrics for an iconic game fish at the northernmost extent of its GOM range. 相似文献
4.
Factors affecting morphological development of the sagittal otolith in juvenile and adult small yellow croaker (Larimichthys polyactis Bleeker, 1877) 下载免费PDF全文
Y. Xiong J. Yang Z.‐H. Zhang H.‐B. Liu T. Jiang T.‐T. Chen 《Zeitschrift fur angewandte Ichthyologie》2015,31(6):1023-1028
The morphology and morphometrics of the sagittal otoliths of small yellow croaker (Larimichthys polyactis) from the southern Yellow Sea were investigated. Study objectives were to evaluate the shape variability and morphometric variables of sagittae of juveniles and adults as related to developmental changes and habit shift. A total of 152 fish were sampled from April to June of 2012 and 2013, along the coastal waters of the Lüsi spawning ground in the southern Yellow Sea. Changes in otolith shapes from the juvenile to the adult were presented with the rim development through the entire‐lobed‐entire transition and with the curvature of the cauda toward the ventral margin. The otolith elongation in the juvenile stage occurred at 10–20 mm standard length (SL) and was likely associated with the formation of otolith accessory growth centers from larvae to juvenile. The L. polyactis sagittal otoliths acquired their definitive shape at 130 mm SL maturity. Ontogeny on otolith shape might be related, for example, to the factors of metamorphic development, feeding habitat, and ambient water salinity, which varied throughout the growth of L. polyactis. 相似文献
5.
The periodicity of otolith growth increments (opaque and translucent zones) from adult red snapper (Lutjanus campechanus) was examined through a mark and recapture study (2005–2010), and laboratory holding of hatchery reared red snapper over
a 2 year period (2002–2004). Wild red snapper (n = 295) were caught hook-and-line, marked with anchor tags, injected with oxytetracycline dihydrate (OTC), and released in
the Gulf of Mexico 15–40 km south of Dauphin Island, Alabama. Marked fish were recaptured up to 2.8 years after release (n = 35) and sagittal otoliths were dissected, sectioned and examined under white and blue-violet light. The number of opaque
growth zones past the OTC mark was compared to time at liberty for each fish and supported an annual periodicity of growth
increment formation. Also, most (87%) of the hatchery reared fish showed two opaque zones that supported an annual increment
formation rate. However, an unusual timing of opaque zone formation was shown for mark-recaptured fish. Based on known timing
of OTC marking, otoliths from mark-recapture fish showed opaque zone formation from late summer (August) to early winter (December).
This fall formation of opaque zones is in contrast to previous studies and its timing may relate to the end of spawning for
this species. 相似文献
6.
Reproductive traits of shovelnose sturgeon Scaphirhynchus platorynchus (Rafinesque, 1820) in the lower Platte River,Nebraska 下载免费PDF全文
M. J. Hamel M. L. Rugg M. A. Pegg R. Patiño J. J. Hammen 《Zeitschrift fur angewandte Ichthyologie》2015,31(4):592-602
We assessed reproductive status, fecundity, egg size, and spawning dynamics of shovelnose sturgeon Scaphirhynchus platorynchus in the lower Platte River. Shovelnose sturgeon were captured throughout each year during 2011 and 2012 using a multi‐gear approach designed to collect a variety of fish of varying sizes and ages. Fish were collected monthly for a laboratory assessment of reproductive condition. Female shovelnose sturgeon reached fork length at 50% maturity (FL50) at 547 mm and at a minimum length of 449 mm. The average female spawning cycle was 3–5 years. Mean egg count for adult females was 16 098 ± 1103 (SE), and mean egg size was 2.401 ± 0.051 (SE) mm. Total fecundity was positively correlated with length (r2 = 0.728; P < 0.001), mass (r2 = 0.896; P < 0.001), and age (r2 = 0.396; P = 0.029). However, fish size and age did not correlate to egg size (P > 0.05). Male shovelnose sturgeon reached FL50 at 579 mm and at a minimum length of 453 mm. The average male spawning cycle was 1–2 years. Reproductively viable male and female sturgeon occurred during the spring (March–May) and autumn (September–October) in both years, indicating spring and potential autumn spawning events. Shovelnose sturgeon in the lower Platte River are maturing at a shorter length and younger age compared to populations elsewhere. Although it is unknown if the change is plastic or evolutionary, unfavorable environmental conditions or over‐harvest may lead to hastened declines compared to other systems. 相似文献
7.
M. Y. Hossain M. S. Arefin M. S. Mohmud M. I. Hossain M. A. S. Jewel M. M. Rahman F. Ahamed Z. F. Ahmed J. Ohtomi 《Zeitschrift fur angewandte Ichthyologie》2013,29(5):1166-1169
The present study describes the length‐weight relationships (LWRs), length‐length relationships (LLRs), Fulton's condition factor (KF), size at first sexual maturity, spawning season, sex ratio and fecundity of the Morari Aspidoparia morar (Hamilton, 1822) (Cyprinidae). Sampling was done using traditional fishing gear jhaki jal (cast net) from July 2010 to June 2011. Total length (TL), fork length (FL) and standard length (SL) were measured with digital slide calipers. Individual body weight (BW) and gonad weight (GW) were determined to an accuracy of 0.01 g for all specimens. The gonadosomatic index (GSI) was calculated and size at first maturity for males and females estimated using GSI and TL as indicators. Female ≥ size at first maturity was used to determine fecundity. A total of 1200 specimens (males = 552, females = 648) ranging from 4.06–12.84 cm TL and 0.53–16.75 g BW were analyzed. The overall coefficient b for the LWR indicated positive allometric growth (>3.00) in males and isometric growth in females (~ 3.00). ancova (analysis of covariance) revealed significant differences between males and females (P < 0.001). All LLRs were highly correlated (r2 > 0.973, P < 0.001). Sizes at first sexual maturity for males and females were 6.0 and 7.0 cm TL, respectively. KF changed little throughout the year and GSI peaked in November to April, indicating the spawning season (GSImax = 15.0 in females, 2.0 in males). Mature females were dominant during the entire spawning season except in April. Mean total fecundity was 6700 ± 3500, ranging from 1860 to 19680. In addition, relative fecundity ranged from 190 to 1200 (mean 560 ± 235) in the Jamuna River. To ensure sustainable management of this species, the protection of mature individuals during the peak spawning season is highly recommended. 相似文献
8.
Age and growth of Alburnus tarichi (Güldenstädt, 1814): an endemic fish species of Lake Van (Turkey)
In total, 240 tarek, Alburnus tarichi, specimens were caught throughout February 2008 in Lake Van, Turkey, a lake with highly salty‐alkaline conditions. Ages, lengths and weights of A. tarichi were determined to estimate length–weight relationships and age composition. Otolith dimensions were also determined. Female : male ratio was 1.47 : 1. Fork length and total weight of specimens ranged from 14.3 to 19.2 cm and 45.76 to 99.63 g, respectively. Maximum age observed was 6 years. Length–weight relationships were calculated for female, male and combined sexes as, W = 0.057FL2.582W = 0.102FL2.513 W = 0.074FL2.544, respectively. Concerning types of growth, negative allometric growth (b < 3) was observed for all tarek specimens. The lagenar otolith was large and flat and marks on otoliths were typically clear, consistent and easy to interpret. Mean otolith length, breadth and weight were determined as 2.592 mm, 2.381 mm, 0.0026 g, respectively. While the otolith weight displayed a curvilinear relationship with the fork length, otolith length and breadth were linearly related to the fork length by height correlation coefficients. 相似文献
9.
Atsushi Nanami Takeo Kurihara Yutaka Kurita Yoshimasa Aonuma Nobuaki Suzuki Hideaki Yamada 《Ichthyological Research》2010,57(3):240-244
The humpback red snapper Lutjanus gibbus (Lutjanidae) is an important species for fisheries in the Kagoshima and Okinawan region of Japan. The present study estimated
the age, growth and reproduction of this lutjanid species in the waters around Ishigaki Island, southern part of Okinawa.
An opaque zone was formed on the otolith every year, and this formation correlated with their spawning season; these zones
were identified as annual rings. Maximum ages of 21 and 24 years were observed for males and females, respectively. The von
Bertalanffy growth parameters clarifying the age–fork length relationship were as follows: L
∞ = 390.5 mm, K = 0.210 year−1 and t
0 = −1.88 year for males, and L
∞ = 303.4, K = 0.256 year−1 and t
0 = −3.05 year for females. The main spawning season was estimated as between May and October, since greater values of gonadosomatic
index for females as well as maturation oocytes and/or postovulatory follicles were observed during those six months. 相似文献
10.
Age and growth were studied for Schizothorax waltoni in the middle reaches of the Yarlung Tsangpo River in Tibet, southwest of China, from April 2004 to September 2006. A total
of 201 specimens were collected ranging from 110 to 580 mm in standard length (SL). In contrast to other otoliths, sectioned
lapillus showed a clear pattern of alternating opaque and hyaline zones. Marginal increment analyses showed that the increments,
each composed of one opaque and one hyaline zone, are deposited annually. Opaque edges were prevalent from May to August.
The von Bertalanffy growth parameters based on sectioned otolith data were L
t
= 689.8{1 − exp[0.051 (t + 3.275)]} for males, and L
t
= 691.1{1 − exp[0.056 (t + 2.466)]} for females. The slow growth and long life indicate that S. waltoni is vulnerable to overfishing and that harvesting strategies for the species should be conservative. 相似文献
11.
Aude Lochet Régine Maury-Brachet Claire Poirier Javier Tomás Michel Lahaye Miran Aprahamian Eric Rochard 《Hydrobiologia》2008,602(1):99-109
Mercury concentration [Hg] was assessed in 20 adult Allis shad Alosa alosa (54–59 cm) and 20 adult Twaite shad Alosa fallax (36–44 cm) collected during their spawning migration in the Dordogne and the Garonne rivers (France). [Hg] was measured in
the gills, dorsal muscle, liver and kidney. Twaite shad exhibited higher [Hg] than Allis shad. Median [Hg] values were [Hg]Gills = 0.33 μg g−1 (dw), [Hg]Muscle = 1.22 μg g−1, [Hg]Liver = 1.99 μg g−1, [Hg]Kidney = 1.93 μg g−1 for Twaite shad and [Hg]Gills = 0.06 μg g−1, [Hg]Muscle = 0.20 μg g−1, [Hg]Liver = 1.18 μg g−1, [Hg]Kidney = 1.08 μg g−1 for Allis shad. In order to understand such differences, we investigated some life history traits of the two species: migratory
history, age (3–6 years), size at age (an expression of growth) and the number of spawning events (0–2 events). The difference
in estuarine residence time between the juveniles of both species, which was assumed to influence [Hg], was investigated using
otolith Sr:Ca ratio. The microchemical analysis revealed a significant difference in the residence time of juveniles in the
estuary (medians are 21 d and 10 d for Twaite shad and Allis shad, respectively) but this residence time seems too short to
influence [Hg] (Allis shad: r
spearman < 0.128; Twaite shad: r
spearman < −0.340). As both species show the same age structure, the influence of age on [Hg] was negligible. The literature shows
that the differences in growth and in the number of spawning events reported in our study are in favour of a higher [Hg] for
Twaite shad than for Allis shad. Although trophic status was not investigated here, the literature reveals that it is another
factor that could produce higher [Hg] in Twaite shad, since its diet includes higher trophic levels than Allis shad.
Guest editors: S. Dufour, E. Prévost, E. Rochard & P. Williot
Fish and diadromy in Europe (ecology, management, conservation) 相似文献
12.
Asiye Başusta Burak Çetinkaya Nuri Başusta 《Zeitschrift fur angewandte Ichthyologie》2020,36(6):888-892
Fish specimens were captured by a commercial bottom trawler at a depth of 50–80 m from Iskenderun Bay (Hatay, Turkey) between December 2017 and May 2018. The bottom trawl gear used was equipped with a 44 mm stretched mesh size net at the cod-end. Blind side and eyed side otolith lengths (OL), otolith breadths (OB) and otolith weights (OW) were measured from each specimen to the nearest 0.001 mm and 0.0001g respectively. A total of 110 fish (43 females and 67 males) were collected. Total length ranged from 20.8 to 28.2 cm and 68.0 to 166.1 g (males) and 21.1 to −28.5 cm and 74.5 to 201.4 g (females). The coefficients of determination between fish weight and otolith weight, and total length and otolith weight (sexes combined) were found as R2 = .7694 (0.77) and R2 = .6274 (0.63), respectively. A moderate positive relationship between the total length-otolith dimensions, and fish weight-otolith dimensions, was also demonstrated. 相似文献
13.
Gonad maturation and spawning of cobia,Rachycentron canadum (Linnaeus, 1766) off the Dungun coast,Malaysia 下载免费PDF全文
T. A. Babatunde S. M. N. Amin N. Romano F. M. Yusoff A. Arshad Y. B. Esa M. Ebrahimi 《Zeitschrift fur angewandte Ichthyologie》2018,34(3):638-645
The reproductive biology of cobia, Rachycentron canadum, from the coastal waters of Dungun, Malaysia was studied from June 2014 to May 2015. From commercial trawls, a total of 201 samples (combined sexes) were collected (fork lengths [FL] 37.5–124.0 cm; body weights 0.5–20.4 g). The overall sex ratio of females to males was 1:0.9, which was not significantly different (χ2 = 2.12, df = 1; p < .05). Estimations of length at 50% maturity (L50) showed that both sexes matured at approximately 75 cm FL; estimated spawning frequency was 6 days. Mean batch fecundity (BF) ranged from 0.55 to 4.32 million eggs. The average number of eggs per gram of ovary was from 2,100 to 5,400 eggs, and relative fecundity 147 eggs/g. There was a weak positive correlation (r2 = .48) between BF and female FL as well as BF with an ovary‐free body weight (r2 = .56), possibly due to females being in a continuous spawning condition and some possibly half‐spent, based on the histological examination of the female gonads. Despite cobia being asynchronous spawners, the gonadosomatic index in both males and females showed peaks in June, November, and particularly March. Based on histological examination, spawning‐capable males were encountered throughout the study period, whereas spawning‐capable females in the late developing subphase were found mostly in March and April. This is the first study on the reproductive aspects of cobia in Malaysian waters. 相似文献
14.
M. Y. Hossain M. A. Hossen M. S. Islam S. Jasmine F. Nawer M. M. Rahman 《Zeitschrift fur angewandte Ichthyologie》2017,33(5):1007-1014
Some aspects of reproductive biology of Pethia ticto (Hamilton, 1822) from the Gorai River of southwestern (SW) Bangladesh were investigated by regular monthly samples for a period of one year during July 2010 to June 2011. A sum of 1200 specimens (male = 454 and female = 746) were collected using cast net, lift net and conical trap. Total length (TL) and Body weight (BW) were measured with slide caliper and digital balance, respectively for each individual. Based on gonadosomatic index (GSI), modified gonadosomatic index (MGSI) and Dobriyal index (DI) first sexual maturity was 4.30 cm TL for male and 4.80 cm TL for female. Also, on the basis of higher values of GSI, MGSI and DI spawning season was ranged from April to September for P. ticto in the Gorai River ecosystem. The fecundity was ranged from 2230–8450 with a mean value of 4779 ± 1578. In addition, there was a significant relationship between total length and fecundity (r2 = .931, p < .001); body weight and fecundity (r2 = .943, p < .001). Therefore, the findings of this study would be very effective for sustainable management of this threatened species in the Gorai River and surrounding ecosystem. 相似文献
15.
Morphometric analysis of otoliths of juvenile crucifix sea catfish Sciades proops (Valenciennes, 1840) 下载免费PDF全文
K. M. F. Freire C. S. Oliveira L. C. Rosa 《Zeitschrift fur angewandte Ichthyologie》2017,33(3):485-490
The objective of this study was to analyze the morphometry of otoliths for Sciades proops juveniles by testing the hypothesis of equality in morphometric relationships for the right and left otoliths, which could then be interchangeably used to estimate fish size or weight. Samples were obtained monthly directly from anglers after each event that took place off the state of Sergipe from March/2014 to April/2015. Anglers used rod and reel during these events, with no restriction on hook size or line thickness. Each fish specimen sampled had their total weight (W, g) and total length (TL, cm) measured and their lapillus otoliths removed and stored separately. Each otolith had its length (OL), width (OWi), and thickness (OT) measured (all in mm) under a stereomicroscope. Otoliths were weighed using a precision scale (OW, g). A total of 883 specimens were sampled: TL = 12.0–60.5 cm and W = 9.8–1880 g. The weight‐length relationship for the juvenile fishes was W = 0.0052TL3.086 and for their otoliths was OW = 0.0002OL3.177. The weight‐length and length‐length relationships fitted for each otolith (right and left) were not statistically different and thus all relations were estimated for grouped otoliths. The length‐length relationships for the otoliths were: OWi = 0.947OL?0.205 and OT = O.484OL?0.698. The relationship estimated for juvenile fish and otolith weight was Wj = 1076.1OW?9.120. For juvenile fish total length and otolith length, width and thickness, the following relationships were estimated: TLj = 4.028OL?3.199, TLj = 4.208OWi?2.091, and TLj = 7.824OT + 3.659, respectively. Relationships between fish and otolith size, and between fish and otolith weight indicated a change in slope close to Lm50, which should be better explored when more adult specimens are available. 相似文献
16.
D. J. Booth 《Coral reefs (Online)》2014,33(1):255-258
Otolith increment structure is widely used to estimate age and growth of marine fishes. Here, I test the accuracy of the long-term otolith increment analysis of the lemon damselfish Pomacentrus moluccensis to describe age and growth characteristics. I compare the number of putative annual otolith increments (as a proxy for actual age) and widths of these increments (as proxies for somatic growth) with actual tagged fish-length data, based on a 6-year dataset, the longest time course for a coral reef fish. Estimated age from otoliths corresponded closely with actual age in all cases, confirming annual increment formation. However, otolith increment widths were poor proxies for actual growth in length [linear regression r 2 = 0.44–0.90, n = 6 fish] and were clearly of limited value in estimating annual growth. Up to 60 % of the annual growth variation was missed using otolith increments, suggesting the long-term back calculations of otolith growth characteristics of reef fish populations should be interpreted with caution. 相似文献
17.
Growth of larval and juvenile Diaphus theta (Pisces: Myctophidae) in the transitional waters of the western North Pacific 总被引:1,自引:1,他引:0
Diaphus theta is one of the most common myctophid fish species in the subarctic and transitional waters of the North Pacific. The growth
of larval and juvenile D. theta was investigated using sagittal otolith increment analysis of specimens caught in transitional waters of the western North
Pacific. Samples taken over a 24-h period demonstrated that otoliths exhibited daily growth cycles, allowing accurate determination
of age. Calcification of the incremental zone of otoliths took place only at night, suggesting that the formation cycle of
the increment of juvenile D. theta was different from that of shallow-water fishes and would be related to their diel vertical migration. The relationships
between standard length (SL) and daily growth increment (D) were expressed as linear equations: SL = 2.65 + 0.141D (r
2 = 0.942) for larvae of 5.1–9.6 mm SL and SL = 3.54 + 0.129D (r
2 = 0.933) for juveniles of 13.7–27.6 mm SL. The growth rates were 0.14 mm d−1 in larvae and 0.13 mm d−1 in juveniles; this is slow compared with tropical or subtropical mycto-phid species, in which growth occurs at about twice
these rates. The larval period, including the metamorphic stage, was long compared with species at lower latitudes and was
estimated to be 71 days. The slow growth rate and long period of larval stage of D. theta would be the life history pattern of high-latitudinal species adapted to a low-temperature habitat.
Received: March 23, 2001 / Revised: July 5, 2001 / Accepted: July 19, 2001 相似文献
18.
Age, growth and reproductive characteristics of creole perch, Percichthys trucha, were investigated in the Negro River, southern Argentina from samples collected seasonally, December 1994–December 1995. Age was estimated via scale and whole otolith reading methods. Total length (n = 413) ranged from 103 to 432 mm, and weight from 12 to 1042 g. Significant differences between the length‐weight relationships of males and females were detected (P < 0.05). Isometric growth was observed in juveniles and males, whereas total population and females exhibited positive allometric growth. The marking pattern in scales and otoliths followed an annual rhythm, with the formation of only one annulus in scales and only one hyaline band in otoliths during autumn‐winter. The oldest males were 5 years old whereas maximum age in females was 12 years from scales and 15 years from otoliths. Because scales were found to underestimate age in individuals older than 4 years, otoliths were considered to be the best structures for creole perch age determination. Gompertz growth parameters based on otolith data were L∞: 428.0 mm, k = 0.46 and t0 = 0.43 for total population (r = 0.90), L∞: 410.7 mm, k = 0.42 and t0 = 0.46 for males (r = 0.91), and L∞: 434.1 mm, and k = 0.49 and t0 = 0.43 for females (r = 0.91). Lengths at first maturity (TL50) were 260 and 241 mm in males and females, respectively, both of which corresponded to ages between 1 and 2 years. Macroscopic gonad inspection and the high percentage of juveniles captured during summer indicated that spawning begins at the end of spring. 相似文献
19.
The brook silverside, Labidesthes sicculus (Cope), is unique in Canadian waters, as it completes its life cycle in 1 year. Previous studies based on scale ageing had
suggested the species was an “annual,” but we confirmed this for the first time by otolith analysis. Growth rates from both
back-calculation, and the Gompertz model, indicated an asymptote near the end of the summer, and average summer growth rates
of 0.77 and 0.70 mm/day, respectively. The Gompertz model gave the best fit (n = 201, r = 0.744) with an L∞ of 85.4 mm TL, and instantaneous growth rate, g, of 0.0264. Back-counting daily growth increments allowed us to show that broods of young fish were produced throughout the
summer, from late May to mid August, with maximum hatch taking place in mid-July. The species is a “batch” (serial) spawner,
with only a fraction of the eggs ripening in the ovary and being released at as yet undetermined intervals. Eggs of the larger
immature fish in the first summer developed from 0.05 to 0.21 mm in diameter (preserved) by fall, and in mature fish of the
following spring and summer, developed to 1.2 mm in diameter (preserved), 1.4 mm fresh, at spawning. Attached to each egg
was a filament averaging 2.0 cm in length, adhesive in nature, and presumably for attachment to vegetation. The egg also had
microscopic hairs on its surface. No evidence was found to support temperature-dependant sex determination, nor were embryos
or sperm found in the ovaries of spawning females, unlike Labidesthes sicculus vanhyningi, (the southern subspecies) which has internal fertilization. The Canadian species possesses a genital papilla through which
the eggs were released, and an apparently much smaller male genital papilla than the southern subspecies. 相似文献
20.
C. Polo‐Silva G. Acevedo S. Siu J. M. Carvajal M. Ixquiac S. Bessudo A. M. Suarez V. Puentes 《Zeitschrift fur angewandte Ichthyologie》2018,34(1):157-161
This study proposes length relationship equations to determine total length of four species of sharks (Carcharhinus falciformis, Mustelus lunulatus, Sphyrna lewini and Carcharhinus limbatus) based on trunk lengths (TrL) and interdorsal lengths (IL) caught in Colombia and Central America Pacific Ocean. In Central American Pacific, data were recorded for C. falciformis, C. limbatus and S. lewini between 2006 and 2012. In the Colombian Pacific, data was recorded in 1994–1995 and from 2006 to 2012 for C. falciformis, S. lewini and M. lunulatus. In the Central American Pacific the IL – TL relationship was acceptable for C. falciformis (r2 = .69) and C. limbatus which presented a good relationship (r2 = .81) where most specimens were juveniles; the same trend was found for S. lewini (r2 = .96). The TL‐TrL relationship estimated for species caught in the Colombian Pacific was significant for C. falciformis (r2 = .98) and for M. lunulatus (r2 = .84); however, for S. lewini this relationship was low (r2 = .55). Results indicate this is a useful tool for fishery statistics and fishery management for elasmobranch species of the Eastern Tropical Pacific. 相似文献