Age and growth of the porthole shovelnose catfish (Hemisorubim platyrhynchos) in the Pantanal.

The porthole shovelnose catfish, Hemisorubim platyrhynchos, is the sixth largest pimelodidae of the Pantanal. Its age and growth were studied using pectoral fin-spines from fish collected in the Cuiabá river basin, Pantanal. The fish, which came from commercial and experimental fisheries, were all caught with hook and line. Growth-ring formation time could not be defined through the Kruskal-Wallis test on marginal increment (H = 4.142; p = 0.247). Nevertheless, decrease in the marginal increment index occurring as waters recede suggests this as the probable time when growth rings form. Estimation of the parameters of von Bertalanffy growth curve, adjusted through nonlinear regression to observed fork lengths, with L(infinity) fixed at 64 cm, were: k = 0.222 year(-1); t(o) = -2.149 years. Individual life span was estimated at 11.4 years. The results suggest that fork length is a good predictor of age for individuals of this species.     

Yield per recruit of the pacu Piaractus mesopotamicus (Holmberg, 1887) in the pantanal of Mato Grosso do Sul, Brazil.

Among the several fish species comercially exploited at the Pantanal of Mato Grosso do Sul, the "pacu" (Piaractus mesopotamicus) stands as one of the most important. Information regarding its exploitation level is necessary for the proper management of its stocks. Between 1996 and 1997 data on total length of the pacu were collected on a monthly basis from specimens caught by professional and sport fishers in the municipality of Corumbá. These data were used to estimate growth parameters and to assess the exploitation level for this species, applying the Beverton and Holt yield per recruit model. Length frequency analysis, carried out with the software FISAT (ELEFAN), was used to estimate growth parameters: 1996: L(infinity) = 87.20 cm; K = 0.34 year(-1); phi(')=3.41; C = 0.74; WP = 0.81; Longevity = 8.40 years; and 1997: L(infinity) = 86.50 cm; K = 0.34 year(-1); phi(')=3.40; C = 0.60; WP = 0.80; Longevity = 8.40 years. The value for t(0) is -0.363 years for mean values of L(infinity) and k. The weight-length relationship, calculated from data derived from experimental fisheries carried out in 1999 and 2000, is described by the equation: W = 0.048LF(2.835). Estimated mortalities and survival rates were: 1996: Z = 1.51 year(-1); M = 0.62 year(-1); F = 0.89 year(-1); S = 21.9%; and 1997: Z = 1.65 year(-1); M = 0.63 year(-1); F = 1.02 year(-1); S = 19.1%. The yield per recruit analysis showed the following values: F(Present) = 0.96 year(-1); F(max) = 0.67 year(-1) ; F(0.1) = 0.51 year(-1) (for L(c) = 26.7 cm). These results suggest that the pacu is overexploited in the area, so that restrictive measures are in need to manage the pacu fisheries.     

Age and growth of the duckbill catfish (Sorubim cf. lima) in the Pantanal.

The Duckbill Catfish, Sorubim lima, is a predator of large South American rivers. The age and growth of S. lima were studied based on the pectoral fin-spines of samples collected from the Cuiabá River, Pantanal. The samples were taken from commercial and experimental hook-and-line fishing. An analysis of the marginal increment suggests that the growth rings are formed once a year during the dry season, from July to September (ANOVA type I: F = 4.183; g.l. = 3 and 104; p = 0.008). The estimate of the parameters that describe von Bertalanffy's growth curve by nonlinear regression of the observed lengths in the age were: L infinity = 56.0 cm (fork length); k = 0.245 year-1; to = -2.605 years. The animals were estimated to have a life span of 9.6 years. The findings indicate that the fork length is a good predictor of the age of individuals of this fish species.     

南渡江上游海南半鲿生物学参数估算

为研究海南半鲿(Hemibagrus hainanensis Tchang 1935)种群生物学及资源动态特征, 2019年1—12月于南渡江上游采集358尾海南半鲿,其体长范围为42—289 mm,体质量范围为1.14—282.79 g。利用FiSATⅡ软件中ELEFAN I法估算南渡江上游海南半鲿种群参数,其资源变动趋势则通过Beverton-Holt动态综合模型进行评估。结果显示:von Bertalanffy生长方程所描述的各参数值分别为L∞=304.5 mm、K=0.49、t0=–0.29,体质量的生长拐点为t=1.95,即TL=202.9 mm。利用Pauly经验公式和长度变换渔获曲线法分别估算出:自然死亡系数(M)为1.05,总死亡系数(Z)为1.22,捕捞死亡系数(F)为0.17及资源开发率(E)为0.14,表明其资源未处在过度捕捞状态。研究结果填补了南渡江上游海南半鲿的种群生长特性及动态特征基础资料的空白,为其种群资源恢复和保护策略的制定提供理论依据。     

Some aspects of the reproductive biology of Spratelloides gracilis (Schlegel) in the Ysabel Passage, Papua New Guinea

Fecundity, length at first spawning, spawning seasonality and ovarian development of Spratelloides gracilis were determined by examining preserved ovaries from fish captured over a 5-year period. Fecundity ( F ) was estimated from the number of eggs in the most advanced ovarian mode and was related to fish length ( L ) by the function: log_e F =3.764 log_eL-7.308, and to weight ( W ) by: log_eW= 1.210 log_eW+7.337. Spawning was observed in most months of the year without any recognizable pattern between the years. Ova diameter frequencies were bimodal but the smaller mode remained stationary regardless of the position of the larger mode. This was interpreted as evidence that individual fish may spawn only once. From data on egg length versus fish length and gonad index versus fish length it was estimated that fish were first capable of spawning at 45 mm (fork length).     

The effect of extreme northerly climatic conditions on the life history of the minnow, Phoxinus phoxinus (L.)

Over its exceptionally wide geographical range the minnow displays a remarkable variability in its life history. In southern England many fish mature after one year and few fish survive to their third birthday. Very few fish spawned for more than one season but a 65-mm female is estimated to spawn up to 3172 eggs over the extended spawning season. In the River Utsjoki in Finnish Lapland maturity was strongly size-dependent and delayed until the fish reached 5, 6 or even 7 years of age, with a maximum age of 13 years at a length of only 75 mm. Unlike some other small-sized species in unproductive environments, individual females continued to spawn successive clutches of eggs though over a much shorter spawning season. The maximum estimated egg production was 824 for a 65-mm fish. Temperature had a strong direct or indirect effect on growth, with significantly lower growth increments in cold summers. At a second Arctic site in eastern Lapland growth rates were higher and maturity earlier, yet clutch size was greatly reduced with a seasonal fecundity estimate of only 314. There were only small differences in size of eggs or larvae between the populations. Evidence from other species indicates that most of the observed changes over the range of the minnow are phenotypic responses to the contrasting environments. However, the different strategies displayed at the two Arctic sites could represent the results of selection for differences in pre- and post-reproductive survival.     

Population parameters of the Pacific flagfin mojarra Eucinostomus currani (Perciformes: Gerreidae) captured by shrimp trawling fishery in the Gulf of California

Shrimp trawling fishery in the Gulf of California captures a wide variety of non-target species of fish, crustaceans, and mollusks that are relatively unknown. The Pacific flagfin mojarra Eucinostomus currani is a frequently found species in these catches, nevertheless, nothing is currently known about its population dynamics. To contribute to the knowledge on this fish species, we studied the size structure, growth, mortality, and the recruitment pattern during the 2004-2005 seasons. A total of 6,078 mojarra were captured from 350 samples, with minimum and maximum lengths of 4.5 cm and a maximum of 21.0 cm. The average total length of the four major cohorts was 11.4, 13.7, 15.6 and 18.0 cm, corresponding to ages 0.9, 1.2, 1.6 and 2.2 years, respectively, being the most abundant the 1.2 year-old group. The instant growth coefficient indicated moderate growth rates (K(s) = 0.81/year, K(E) = 0.85/year), corresponding to individuals living between 3.5 to 3.7 years. The estimated asymptotic lengths was L (infinity) = 21.8 cm. In general, the population could be considered healthy: natural mortality (M = 1.53/year); total mortality (Z = 2.73/year); condition factor (K = 0.01072); fishery mortality (F = 1.2/year) and exploitation rate (E = 0.43/year). The maximum reproduction period almost coincided with the closed season for shrimp fishing (March to August), thus we concluded that survival of the species is ensured because reproduction is indirectly protected.     

Dana swimming crab growth Callinectes danae (Decapoda: Portunidae) from Margarita Island, Venezuela

Callinectes danae is a common species captured with crab traps in nearby areas of coastal lagoons in Margarita Island. Although its considerable economic importance as a fishery resource, few studies have been done on population dynamics and its fishery potential in local coastal environments to support decision making in fishery administration. We present growth pattern details of Callinectes danae to better estimate its population size and exploitation feasibility. For this, we analyzed a total of 3 623 specimens that were monthly captured in crab pots by artisanal fishermen in Las Marites lagoon, from October 2007 to September 2008. The length-weight ratio was determined, and growth parameters estimated from both length and weight curves of the von Bertalanffy model. The general sex ratio showed no significant difference between males and females (chi2 = 0.04, p > 0.05). However, values of slopes b between males and females were significantly different (t(s) = 2.75, p < 0.05), as well as intercepts a (t(s) = 2.44, p < 0.05). Thus, the length-weight ratio was determined separately: W = 7.48e(-5)*L(2.98) for males and W = 1.21e(-4)*L(2.87) for females, indicating a negative allometric growth in both sexes. Growth parameters were established as: L(infinity) =134.80mm, W(infinity) = 166.04g and k = 0.86/yr for males; L(infinity) = 122.35mm, W(infinity) = 118.45g and k = 0.63/yr for females. Lifespan was estimated at 3.05 years for males and 4.24 years for females. We concluded that Callinectes danae is a species with short lifespan and moderately rapid growth. The coefficient of variation values (CV), of the phi-prime growth performance index (?'), showed a different growth pattern compared to those obtained in other regions. We propose that a management strategy will be the periodical review of the minimum capture size for fishing area, after the great variability found in growth parameters.     

Growth, mortality and exploitation rate of Priacanthus arenatus (Perciformes: Priacanthidae), in the trawl fisheries of northeast Venezuela

We analyzed growth, mortality and exploitation rate of Priacanhus arenatus, captured by the shrimp trawling fishery (1989-1996), in northeastern Venezuela. The growth coefficient (K) and the asymptotic length (L8) were estimated by length-frequency data using the Battacharya method and other routines of the FISAT program. Total mortality (Z) and exploitation (E) rates were obtained by length-converted catch curve analysis, based on length-frequency data, and the Berverton and Holt's yield per recruit model, respectively. The mean growth parameters L and K were estimated as 474.7 mm and 0.69 year(-1), respectively. Mean total mortality was 4.03 and the exploitation rate range was 0.70-0.80. Results indicated that the population is overexploited.     

Age, growth and yield per recruit analysis of the pintado Pseudoplatystoma corruscans (Agassiz, 1829) in the Cuiabá River basin, Pantanal Matogrossense, Brazil.

The age and growth of the pintado Pseudoplatystoma corruscans were studied during the period from May 1994 to May 1995. The standard length ranged from 52 to 145 cm and the weight from 1.3 to 41 kg. The biometric relationship between the standard length (Ls) and total length (Ltotal) and between the total weight (Wt) and the standard length (Ls) were obtained for the species, being respectively: Ltotal = 3.296 + 1.069 * Ls and Wt = 0.00624 * Ls(3.134). The condition factor calculated monthly suggests the spawning season to be between the months of February and March. The age was estimated by counting growth rings present in the spines of the pectoral fins, and 10 age classes were detected. The mean distance of the last ring until the border of the spine suggests that the period of least growth is between July and September (dry period). Von Bertalaffy's equation describing the growth of the pintado is: Lt= 183 * [1 - exp - 0.085 * (t + 3.274)]. Total mortality was Z = 0.24 year(-1) and natural mortality M = 0.20 year(-1). As the present level of exploitation, F = Z - M = 0.04 year(-1), we conclude that the pintado stock was still underexploited in the Pantanal in the sampled period.     

Biological attributes of age-0 lake sturgeon in the lower Peshtigo River, Wisconsin

Lake sturgeon Acipenser fulvescens are imperiled throughout the Laurentian Great Lakes basin. Efforts to restore this species to former population levels have been ineffective due in part to limited information regarding its early life history. The objectives of this study were to characterize the larval drift and biological attributes of age‐0 lake sturgeon in the lower Peshtigo River, Wisconsin. Lake sturgeon larvae were captured from May to June 2002 and 2003 using drift nets, while age‐0 juveniles were captured from June through October 2002 and 2003 using wading, snorkeling, backpack electrofishing, and haul‐seine surveys. Larval drift occurred within 14 days of adult spawning and extended from 1 to 3 weeks in duration, with two peaks in the number of fish drifting downstream each year. Larvae had a median total length (TL) of 19 mm (range: 13–23; N = 159) in 2002 and 18 mm (range: 13–24; N = 652) in 2003. Catch‐per‐unit‐effort for larvae was 0.18 fish h^?1 m² and 0.94 fish h^?1 m² in 2002 and 2003, respectively. Age‐0 juvenile lake sturgeon exhibited rapid growth (i.e. 2.57 mm day^?1 in TL and 0.66 g day^?1 in wet weight) throughout summer and fall months; relative condition of fish in both years was approximately 100, indicating good condition. Absolute abundance of age‐0 juveniles in 2003 was estimated at 261 fish using the Schnabel estimator. The results from this study indicate that the lower Peshtigo River contains important nursery habitats suitable for age‐0 lake sturgeon.     

Length–weight relationship of seven fish species from the temporary habitat,Pantanal wetland,Brazil

The length–weight relationships (LWRs) were estimated of seven fish species from 22 localities in the Pantanal wetland between Mach 2006 and April 2011. Fish were sampled using seven gill nets (20 × 1.5 m; mesh size: 12, 15, 18, 20, 25, 30 and 50 mm between opposing knots) and throw traps (made of 1 m³ metal cubes, covered by a 1.5 mm nylon mesh). Standard length and weight were measured and used to calculate the LWR parameters. Values for parameter b varied from 2.87 (Apistogramma borellii) to 3.29 (Hoplerythrinus unitaeniatus) and, such values are within the expected range.     

Age and growth of king and Spanish mackerel larvae and juveniles from the Gulf of Mexico and U.S. South Atlantic Bight

Synopsis Sagittal otoliths from 50 king mackerel 2.9–13.0 mm SL and 72 Spanish mackerel 2.8–22.0 mm SL collected off the southeast U.S. were examined whole at 400 × using a compound microscope-video system. Otoliths of both species had visible, presumably daily, growth increments as well as finer subdaily increments. Otolith growth was directly proportional to growth in standard length for king (r² = 0.91) and Spanish mackerel (r² = 0.86). Spanish mackerel were estimated to be 3–15 d old with a mean absolute growth rate (SL/number of growth increments) and 95% confidence interval of 1.15 ± 0.07 mm · d^–1. The least squares linear equation: SL = –1.30 + 1.31 (age in days), with r² = 0.67 and p < 0.001, described the relationship between length and age. There was a significant positive relationship between absolute growth rate and fish length. King mackerel were estimated to be 3–15 d old with a mean absolute growth rate of 0.89 ± 0.06 mm d^–1. The least squares linear equation: SL = 0.37 + 0.82 (age in days), with r² = 0.77 and p < 0.001, best described the relationship between length and age. The relationship between growth rate and fish length was not significant. The growth rate of king mackerel was slightly higher for fish from the Mississippi River plume than from all other locations combined, while Spanish mackerel growth rates were not significantly different.     

怒江东方墨头鱼的年龄结构与生长特性

2006年10月至2008年10月于怒江采集东方墨头鱼(Garra orientalis)136尾,体长54～167mm,体重3.0～114.6g。研究了其年龄、生长等生物学特性,通过耳石轮纹估算东方墨头鱼的年龄,显示怒江东方墨头鱼由10个年龄组组成。耳石半径与体长关系为:L=0.061R1.131(n=125,R2=0.907),体长与体重关系为:W=0.1×10-4L3.160。von Bertalanffy生长参数由退算体长估算:雄性L∞=224.79mm,k=0.094/年,t0=0.51年;雌性L∞=228.91mm,k=0.091/年,t0=0.639年;总体L∞=227.78mm,k=0.091/年,t0=0.588年。体重生长拐点雄性12.15龄、雌性13.75龄。     

The life history of rock gurnard (Trigloporus lastoviza, Brünn. 1768) in the Saronikos Gulf

Age, growth and reproduction of rock gurnard in the Saronikos Gulf (Greece) were studied. Otoliths from 638 specimens (sex combined) were read for age determination. The body length-otolith radius relationship was found linear (L = -18.0 + 4.99 _xR; where L = fish length in mm, R = otolith radius 20 X). The life span of females seemed to be longer than that of males, indicating a differential mortality with sex. The growth was lower than that in the Catalane Sea. The maximum age of fish collected was VIII and the maximum fork length estimated by von Bertalanffy equation was 356 mm. Weight increased as the 3.054252 power or the length. Reproduction was observed to take place between winter and early spring and occasionally in early winter. Males began to mature after completion of the second year and the females after the third. The exploitation rate was rather high, which suggests that the rock gurnard stock was overfished in Saronikos Gulf. The male to female ratio was usually 1:1.     

Age and growth of the Black Sea turbot, Psetta maxima (Linneaus, 1758) (Pisces: Scophthalmidae), estimated by reading otoliths and by back-calculation

Age and growth of the Black Sea turbot, Psetta maxima, were determined from a total of 1445 individuals collected along the eastern Black Sea coast between 1990 and 1996. Age was estimated by interpreting growth rings in whole and broken sagittal otoliths. The former method underestimated the age over 5 years, and a maximum age of 11 years was observed by the latter. Marginal increment analysis clearly showed that a single annulus is formed in early summer each year. Growth in length differed between sexes, and females attained a larger size than males at the same age. No significant difference was found between the mean observed total length (TL), the back‐calculated TL derived from radius measurements and the TL estimated from otolith size–fish size relationship. The von Bertalanffy growth parameters estimated by the length‐at‐age data were: L_∞ = 96.24 cm; K = 0.119 year^?1; t₀ = ?0.01 year for the entire population.     

Age and growth of albacore Thunnus alalunga in the North Pacific Ocean

The age and growth of North Pacific albacore Thunnus alalunga were investigated using obliquely sectioned sagittal otoliths from samples of 126 females and 148 males. Otolith edge analysis indicated that the identified annulus in a sagittal otolith is primarily formed during the period from September to February. The assessments of the fish age at first annulus formation indicated that the first annulus represents an age of <1 year. This study presents an age estimate (0·75 years) for the formation of the first annulus. The oldest fish ages observed in this study were 10 years for females and 14 years for males. The von Bertalanffy growth parameters of females estimated were L(∞) = 103·5 cm in fork length (L(F) ), K = 0·340 year(-1) and t(0) = -0·53 years, and the parameters of males were L(∞) = 114·0 cm, K = 0·253 year(-1) and t(0) = -1·01 years. Sexual size dimorphism between males and females seemed to occur after reaching sexual maturity. The coefficients of the power function for expressing the L(F) -mass relationship obtained from sex-pooled data were a = 2·964 × 10(-5) and b = 2·928.     

Size frequency distribution and growth of the crabs Callinectes arcuatus and C. bellicosus (Decapoda: Portunidae) in Las Guásimas coastal lagoon, Mexico

Information on size frequency distribution, the width-weight relation and growth parameters of the crabs Callinectes arcuatus and C. bellicosus is presented. The data comes from samples taken with a trawl net both day and night on a monthly basis from March 1998 to February 2000 in a coastal lagoon from Gulf of California. C. bellicosus (n=878) was more abundant than C. arcuatus (n=357) and its size frequency distribution presented carapace width CW ranges of 8.4-166 mm and 9-130 mm respectively. Both populations were mainly represented by juveniles (75 mm in CW) ranging from 37 to 75 mm in CW, and adults (>75 mm in CW) between 76 and 90 mm in CW. In both species the width-weight relation showed that males grow more than females, with an isometric growth tendency being observed. The growth parameters for C. arcuatus estimated using the von Bertalanffy Model, were: K = 0.84 year(-1), L infinity = 140 mm to = -0.12 for C. arcuatus, and K= 0.9 year(-1), L infinity = 169 mm to = -0.11 for C. bellicosus. These results showed that the relative age at which maximum growth is attained is between three and four years for both species.     

Population ecology of Red-bellied Piranha Pygocentrus nattereri Kner, 1858 (Characidae: Serrasalminae) in the Negro River, Pantanal, Brazil

This study defined some population parameters for growth of the Red-bellied Piranha (Pygocentrus nattereri) in the Pantanal, based on the bimonthly length-frequency distribution of individuals in samples taken from October 2005 through August 2008 in the Negro River. The samples were taken by means of gill nets and cast nets, with meshes of 1.5?C8?cm between adjacent knots. The standard length of the fish ranged from 10.2 to 30.2?cm with a mean of 20.51?±?3.39. The gonadosomatic index (GSI) varied significantly among months (F?=?5.45; p?<?0.01), it was significantly higher from October to February, and was positively correlated and synchronized with day length (rs?=?0.92; p?<?0.01) and rainfall (rs?=?0.70; p?<?0.01). It was desynchronized from and not correlated with river level (rs?=?0.12; p?=?0.69). The GSI reached the highest values and ripe individuals were more frequent in December, prior to the months of highest river levels from February to April. The estimated growth parameters were L???=?31.8; k?=?0.45; Rn?=?0.204. In the Pantanal, P. nattereri has a life expectancy (6.9?years) compatible with the 7 cohorts indicated by the growth curve. Sexual maturation occurred at around 15.4?cm, after 1.6?years.     

Hook selectivity of the pacu Piaractus mesopotamicus (Holmberg, 1887) in the Pantanal, the state of Mato Grosso do Sul, Brazil.

The Pacu Piaractus mesopotamicus is the most captured fish species in the Pantanal, Mato Grosso do Sul State, and since 1994, its maximum sustainable yield had already been exceeded. Its capture is carried out only by hooks, as mesh gears are forbidden either for professional or for recreational fishing. The aim of this study was to determine selectivity for different hook sizes used in P. mesopotamicus fishing and to verify which sizes capture only adults. Data were collected in the rivers Miranda, Aquidauana, and Vermelho, in January, March, and April 2002. Six longlines with eight hook sizes were used and we adopted the hook opening as a measure related to selectivity. Different hooks captured individuals of the same length and their medians were similar, evidencing the great overlap among sizes. Regression results showed no significant relationship between ln[c2(l)/c1(l)] and total length of captured individuals. In addition, the Kolmogorov-Smirnov test also did not detect significant differences in the size of captured fish. Several hypotheses, such as the selectivity models, shape of selection curves, scarcity of large fishes, and behavior are used in order to explain the absence of hook selectivity for this species. Size of recruitment for this gear was 28 cm of total length, when individuals are still immature.