Monthly Length-frequency Distributions Research Articles

Estimate of Growth Parameters of Penaeus kerathurus (Forskäl, 1775) (Crustacea, Penaeidae) in the Northern Adriatic Sea.

Crustacean fisheries are gaining prominence globally amid a decline in finfish stocks. Some decapod crustacean species have experienced increased landings in response to shifting market demands and environmental dynamics. Notably, the caramote prawn (Penaeus kerathurus-Forskål, 1775) in the northern Adriatic Sea, Geographical Sub Area (GSA) 17, has risen in both landings and economic importance in recent years. However, despite its significance, comprehensive information on fishery-dependent data, age, and growth in this region remains lacking. To address this gap, this study employs modal progression analysis and the ELEFAN approach, utilizing the "TropFishR" R package and newly developed functions, including bootstrapping procedures. These advancements aim to overcome issues identified in previous versions and enhance the accuracy and reliability of age and growth estimations. The study leverages one year of monthly length-frequency distributions (LFDs) collected from commercial bottom trawls in the northern Adriatic Sea. The results of the analysis confirm the presence of sexual dimorphism in the caramote prawn species, with females exhibiting faster growth rates compared to males. Additionally, the growth performance index supports this observation, further underscoring the importance of accounting for sexual dimorphism in growth modeling and fisheries management strategies. By contributing to a growing body of knowledge on the growth dynamics of the caramote prawn, this study provides valuable insights for sustainable fisheries management in the northern Adriatic Sea. Understanding the age and growth patterns of key crustacean species is essential for developing effective conservation measures and ensuring the long-term health and productivity of marine ecosystems. The findings of this study serve as a foundation for informed decision-making and proactive management practices aimed at preserving the ecological integrity and economic viability of crustacean fisheries in the region.

Reproduction, Growth, Mortality and Yield of the Goatfish Upeneus sulphureus in Northern Bay of Bengal, Bangladesh

Information on stock condition and reproductive biology are important for fisheries conservation and management planning. This study examined reproduction, growth, mortality and yield of sulphur goatfish (Upeneus sulphureus Cuvier 1829), which is a low-value food fish abundantly caught as bycatch in artisanal and industrial fishing from the southeast coast of Bangladesh at northern Bay of Bengal. Data were collected monthly obtaining samples from local fish landing center. The gonadosomatic index indicated that U. sulphureus spawns twice a year during January–May and August–October. Fecundity of the fish was positively correlated with the body and gonad weight, and varied from 15 128–97 274 eggs with fish weight 11.30–58.73 g. Monthly length–frequency distribution was analyzed through FISAT software, thus the estimated seasonalized von Bertalanffy growth parameters were L∞ = 21.80 cm, K = 0.54 per year, C = 0.5, WP = 0.1 and Rn = 0.300, respectively. Moreover, the value of seasonalized total mortality coefficient Z (2.24) was smaller than that of the non-seasonalized Z (4.16). The instantaneous natural mortality and fishing mortality, calculated for non-seasonalized total mortality, were 1.31 and 2.86, respectively. Furthermore, the high exploitation rate (E = 0.69) was close to maximum exploitation level (Emax = 0.75) in yield-per-recruit analysis, suggesting that U. sulphureus is being exploited at the MSY (maximum sustainable yield) level. Therefore, further increase in fishing effort may reduce U. sulphureus stocks in the coastal waters of Bangladesh.

Population structure of Sind sardinella Sardinella sindensis (Day, 1878) in northern Persian Gulf and Oman Sea, Iran

The population dynamics of Sardinella sindensis (Day, 1878) was studied from samples in the commercial fishery in the coastal waters of the Persian Gulf and Oman Sea. A total of 12,898 specimens were collected through monthly sampling of boat purse seine and beach seine catches. Total length of the sampled fishes ranged from 5.0 to 19.9 cm. The von Bertalanffy growth parameters determined using monthly length frequency distribution were asymptotic length (L∞ = 21 cm), growth coefficient (K = 1.2 year-1) and age at zero length (t0 = -0.14 year). The estimated value for longevity (tmax) was 2.5 years. The probability of capture was calculated as Lc25=10.2 cm, Lc50=10.9 cm and Lc75=11.8 cm total length. Four cohorts with mean lengths of 7.2, 11.7, 15.7 and 18.6 cm were discerned in a year, with two recruitment peaks. The calculated length-weight equation was W= 0.0078 L3.02. The instantaneous rates of mortality (Z) was estimated as 4.02, with natural mortality M=2.19 and fishing mortality F=1.83 year-1. The exploitation rate (E) was 0.46, which was found to be reasonable for current fishing effort. From the yield-per-recruit analysis, Emax was estimated as 0.79, confirming that the stock is under optimum exploitation.

A review of biological patterns of the blue-red shrimp <em>Aristeus antennatus</em> in the Mediterranean Sea: a case study of the population of Antalya Bay, eastern Mediterranean Sea

During three surveys between September 2009 and June 2011, a total of 20867 specimens of A. antennatus were caught from the 127 successful hauls with a total towing time of 219.5 h. Carapace length ranged between 12-61 mm for females (mean length, 35.8±8.2 mm) and 14-35 mm for males (24.8±3.4 mm). The two-way MANOVA shoved that depth had a significant effect on the abundance (p 27 mm) were recorded in June, July and August. The monthly gonadosomatic index of A. antennatus females changed seasonally, reaching a maximum value between July and August. The length-weight relationships in female and male specimens exhibited a strong negative allometry. The monthly length-frequency distributions showed that females of A. antennatus exhibited a maximum of six modal size groups per year. The recruitment of young-of-the-year took place mainly between January-April. The fishing mortality, reference point (F0.1) of fisheries mortality and exploitation rate were 0.498 year-1, 0.444 year-1 and 0.524 year-1, respectively. The fishery activity and the biological aspects of A. antennatus in the Antalya Bay have a lot of common and non-common points with other areas of the Mediterranean Sea. The above-men-tioned differences could be attributed to the different oceanographic and environmental parameters in the present study area.

Age, growth, and recruitment patterns of juvenile ladyfish (Elops sp) from the east coast of Florida (USA).

Ladyfish (Elops sp) 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−1 in 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−1 in 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.

Age and size compositions, habitats, growth and reproductive characteristics of a terapontid (Pelates octolineatus) in coastal waters

This study of Pelates octolineatus is the first to use individually aged fish to describe the life cycle of a terapontid, a speciose and abundant Indo-West Pacific family. On the lower west Australian coast, this species uses dense seagrass as a nursery area and, after ~1 year of life when approaching 100mm in total length (TL), moves into deeper waters over sparser seagrass where it matures at the end of its second year at ~140–170mm. The maximum TL and age were 256mm and 10 years. A modified von Bertalanffy curve, allowing for a linear increase in the growth coefficient with age, improved the fit to the lengths at age of older P. octolineatus. Growth was even better described by extending this model to allow for seasonality through incorporating a sine-based curve. This model described well the seasonality exhibited by modal progressions in monthly length–frequency distributions. Instantaneous growth rates, particularly of the youngest age classes, peaked in the warm, summer months and the amplitude of seasonal change in these rates declined with increasing age. Gonadal recrudescence occurred in early spring as temperature and day length increased and spawning peaked in late-spring to mid-summer when temperatures were approaching their maxima.

Sexual seasonal growth of the European anchovy (Engraulis encrasicolus) caught by mid-water trawl and purse seine in the southern Black Sea

The seasonal growth pattern and size composition of the European anchovy, Engraulis encrasicolus caught by mid-water trawl and purse seine was studied in the southern Black Sea between October 2010 and April 2011. Total length (TL) and size distribution of females caught by purse seine was higher than males and females obtained from mid-water trawl (P < 0.05). The seasonal von Bertalanffy growth parameters, computed from monthly length–frequency distributions, were estimated as asymptotic length to which the fish grow (L∞) = 13.01 cm TL, growth-rate parameter (K) = 0.993 year−1, amplitude of the sinusoidal growth oscillations (C) = 0.800, and the time of the year when the growth rate is slowest, the winter period (WP) = 0.298 for males and as L∞ = 13.69 cm TL, K = 1.249 year−1, C = 0.950, and WP = 0.151 for females caught by mid-water trawl. The seasonal von Bertalanffy growth parameters for anchovy obtained from purse seine fishing in the Rize region were estimated as L∞ = 14.00 cm TL, K = 0.800 year−1, C = 0.980, and WP = 0.212 for males and as L∞ = 13.93 cm TL, K = 0.994 year−1, C = 0.725, and WP = 0.319 for females. The period of slowest growth for males and females estimated between February and April, which is the period with a relatively low water temperature and consequently anchovy in the southern Black Sea have a seasonal growth pattern.

Hake, Merluccius merluccius L., in the northeastern Mediterranean Sea: a case of disappearance

Summary Hake was not an important commercial fish in the northeastern Levant until the 1990s when a sudden increase in landings was experienced. However, following a series of profitable years, landings declined sharply. The rapid development of the trawl fleet played a role in the decline; however such an episodic event cannot be explained within the fisheries context alone. In this study the results of sparse historical trawl surveys were evaluated together with oceanographic data, and the impact of hydrographical changes on the appearance/disappearance of hake in the Levant was considered. The formation and movement of different water masses in the area seem to have primary importance for the species. The winter occurrence of modified Atlantic water that temporarily intrudes in the region may favour hake. Parallel with the increase in hake, an increase in clupeid species not common in the area was also observed. The change in the hydrography of the region, which was probably linked to the cold period that prevailed at the same time, temporarily led to an additional late summer pulse in the production cycle. The consequent increase in clupeids along with the changes in the hydrology favoured the advent of clupeid-eating hake in the NE Levant. The growth pattern result of the modal shift in monthly length-frequency distributions also showed that the species underwent a rapid growth phase in winter, which was most likely associated with intense feeding.

Sexual seasonal growth variation and reproduction biology of the rock pool prawn, <em>Palaemon elegans</em> (Decapoda: Palaemonidae) in the southern Black Sea

The seasonal growth pattern and reproductive biology of the rock pool prawn, Palaemon elegans , were studied in the southern Black Sea between February 2002 and January 2004. The seasonal von Bertalanffy growth parameters, computed from monthly length frequency distributions, were estimated as L ∞ = 47.8 mm total length (TL), K = 1. 115 year -1 for females and as L ∞ = 41.1 mm TL, K = 1.654 year -1 for males. The seasonal oscillation in growth rate for females (C = 0.904) was larger than it was for males (C = 0.586). The slowest period of growth corresponded to June in females and February in males. The size at sexual maturity for females (TL 50 ) was estimated as 33.8 mm TL. Ovigerous females were recorded from March to August and juveniles appeared in the benthic population in August. The ovarian development of the rock pool prawn was most probably initiated by photoperiod, whereas embryo development was accelerated with increasing water temperatures.

Seasonal growth and reproduction biology of the Baltic prawn, Palaemon adspersus (Decapoda: Palaemonidae), in the southern Black Sea

Seasonal growth pattern and reproductive biology of the Baltic prawn, Palaemon adspersus, were studied in the southern Black Sea between February 2002 and January 2004. The seasonal von Bertalanffy growth parameters, computed from monthly length–frequency distributions, were estimated as L∞ = 62.99 mm TL, K = 1.190 year−1, C = 0.815, and WP = 0.847 for females and as L∞ = 49.63 mm TL, K = 1.085 year−1, C = 0.011, and WP = 0.407 for males. Growth performance index of females (Φ′ = 3.67) was greater than it was for males (Φ′ = 3.43). Based on latitudinal gradients, water temperature negatively affected Φ′ of P. adspersus. Sexual dimorphism in size was evident, females being larger than males. This typically shallow water species was observed in water depths as deep as 30 m. Compared to shallower water depths, larger individuals were observed in deeper water depths. The size at sexual maturity for females (TL50) was estimated as 53.60 mm TL. Ovigerous females were recorded from March to August and juveniles appeared in the benthic population in August. Ovary development was related to photoperiod and occurrence of ovigerous females was linked to increased water temperature.

Annual growth and age composition of the squat lobster <i>Cervimunida johni</i> off northern-central Chile (1996-97)

The MULTIFAN method was used to analyse a series of monthly length-frequency distributions of the squat lobster Cervimunida johni Porter (1903) (Galatheidae), for the estimation of growth and age composition in the fishing area off Coquimbo (29°59’S-71°22’W), in the northern-central area off Chile. Length frequency data (LFD) were collected from commercial catches made between 28°S and 32°10’S from September 1996 to September 1997. MULTIFAN distinguished 11 age classes in the LFD of males and 9 age classes in the LFD of females. This is an important result because usually only three to four age classes have been reported by analysing annual length-frequency data. Males and females were recruited to the fishery at 19.7 and 18.8 mm carapace length (CL) respectively. The von Bertalanffy growth parameters were estimated as K = 0.151 yr -1 and CL ? = 52.8 mm for males, and K = 0.174 yr -1 and CL ? = = 45.60 mm for females. Males reached larger sizes than females, which is in agreement with the growth of other Galatheids.

Age and growth of the ommastrephid squid Todarodes sagittatus from the western Mediterranean Sea

Age and growth of Todarodes sagittatus were estimated based on statolith analysis from individuals (N=352; 81–418 mm mantle length) caught by bottom trawlers during a year of sampling in the western Mediterranean. The daily nature of statolith increments was indirectly validated comparing the mean age of consecutive monthly modes (identified on the monthly length–frequency distributions) with the corresponding increase of 30 days. In agreement with other ommastrephids, results confirmed the following points: (1) lifespan lasts nearly a year; (2) growth rates decrease with age; (3) when adult, females have higher growth rates than males; and (4) females mature about a month later than males. Significant correlation was found between hatching (which occurred throughout the year but with a peak in November) and temperature at 50 m depth (where it is thought that hatchlings inhabit). Age and growth results were compared with those obtained in a similar work carried out in north-west Africa (Arkhipkin et al., 1999). Comparisons suggested that due to higher growth rates in juveniles, southern populations reach maturity and consequently decrease somatic growth at younger ages and smaller sizes than northern squid, which attain larger sizes as a result of maintaining fast growth and delaying maturation. Greater growth rates in juveniles from west Sahara could be explained by higher temperatures in this area than in the Mediterranean.

Age and growth, reproduction and diet of a sublittoral population of the rock goby Gobius paganellus (Teleostei, Gobiidae)

Basic biological information for a sublittoral population of the rock goby Gobius paganellus Linnaeus, 1758 is presented based on a 2-year study involving 1680 specimens. The length–weight relationship was given by TW = 0.0089 * TL3.163 (where TW= total weight in g; TL= total length in mm). Age at length data were inferred by modal analysis of the monthly length–frequency distributions. The parameters of the fitted Von Bertalanffy growth equation (with seasonal component, birth date on the 1st of January) were L ∞ = 13.8 cm; K = 0.73 yr−1; t o = −0.22 yr; C = 0.95; W = 0.07. This growth rate is much higher than that described for northern Europe populations (where K is about 0.3 yr−1) and is probably associated with a shorter life span. Macroscopic examination of the gonads, and analysis of the monthly values of the gonadosomatic index, indicated that reproduction occurs in winter and early spring, with a maximum in February and March, when water temperatures are lowest. Individuals become sexually mature around 6–7 cm TL, a size that can be reached in less than 1 year. By contrast, individuals of this goby in the British Isles mature in their second or third year. Stomach contents were mainly small benthic invertebrates, predominantly crustaceans.

Age and growth of <i>Aphia minuta</i> (Pisces, Gobiidae) from the central Adriatic Sea

Aphia minuta (Risso, 1810) is by far the most common pelagic gobiid of the Adriatic Sea and it is seasonally exploited by some local small-scale fishing fleets. Despite this, very few data on its biology in this area have been reported to date. Accordingly, age and growth of A. minuta were investigated by counting microincrements (daily rings) in the sagittal otoliths of 262 specimens caught in the central Adriatic between May 1996 and March 1997. Age of fish from 14 to 55 mm total length ranged between 42 and 275 days, confirming the short life span of this species. The von Bertalanffy growth parameters estimated by the age-length data pairs for the whole population were: L = 68.7 mm; K = 1.55 year-1; t0 = 0.077 year. The analysis of the monthly length-frequency distributions showed the simultaneous presence in late spring-early summer of two main cohorts which, together with the back-calculated hatch date distribution, indicated a more extended spawning period than previously reported in the literature. Because the fishery for A. minuta in the central Adriatic exploits the spawning stock it should be monitored and, if necessary, regulated.

Population structure and growth of Donax trunculus (Bivalvia: Donacidae) in the western Mediterranean

A comparison of shell growth in Donax trunculus (collected between 1988 and 1990 of Cullera, Spain) has been carried out using an analysis of cohort progression in monthly length frequency distributions, hyaline surface shell growth rings and internal microgrowth bands. In the Mediterranean there are two periods of recruitment of D. trunculus, one in the summer (July to September) and the other in winter (December to February). Clams recruited to the population in winter display a clear cessation in shell growth during the following summer which may possibly be correlated with spawning, whereas individuals of the summer recruited cohort show no growth cessation the following summer and continue to deposit shell during this period. The normally opaque shell of D.trunculus reveals the presence of translucent hyaline growth rings when the shells are backlit by a strong light source, and these have been shown to be laid down in the shell during summer months. Formation of a hyaline ring is accompanied by a narrowing of the microgrowth patterns present in shell sections. Both the hyaline rings and the length frequency distributions have been used to determine the age and growth rate of D. trunculus.

Growth, movements and diet of the terapontid Amniataba caudavittata in an Australian estuary

Samples of Amniataba caudavittata were collected from the Swan Estuary in south-western Australia between February 1977 and December 1980, using seine nets in inshore shallow waters and gillnets and otter trawls in offshore waters. Although fish could only be aged using otoliths until they were 18–22 months old, they had by that time reached c. 75% of their final length. The mean lengths of the cohorts determined by using MIX, which analysed each of the monthly length-frequency distributions independently, were similar to those yielded by MULTIFAN, which constrains the means of each of the sequential and corresponding cohorts to a von Bertalanffy growth curve. Consequently, the von Bertalanffy growth curve parameters determined by MULTIFAN and those derived from the use of the means produced by MIX were similar. The clear cut trends exhibited by the progression of modal lengths in successive samples, and their close correspondence to the trends shown by the growth curves, demonstrate that many A. caudavittata live for at least 3 years. Growth was seasonal and confined to the warmer months of the year. The apparent negative growth recorded in winter can be attributed to a tendency for the smaller representatives of the different cohorts to remain inshore at that time and thus to be more susceptible to capture by seine netting, the main sampling method. Offshore movements by larger fish in the winter allow those fish to remain in the high salinities found beneath the pronounced haioclines that form in the deeper waters of this estuary during the heavy freshwater discharge that occurs typically at that time of the year. Adult A. caudavittata move into the upper estuary where spawning occurs, with considerable numbers of the resultant juveniles then moving downstream into the middle estuary. A, caudavittata is a benthic omnivore, with the 0+ age class ingesting algae and a range of small crustaceans, while older fish prey to a greater extent on polychaetes.

Growth, mortality and yield-per-recruit of deep-water royal red prawns (Haliporoides sibogae) off eastern Australia, using the length-based MULTIFAN method

The MULTIFAN method of Fournier et al. was used to analyse a series of monthly length-frequency distributions of deep-water royal red prawns (Haliporoides sibogae de Man, 1907, Solenoceridae) for the estimation of growth, mortality and yield-per-recruit. Length data were collected from commercial catches made between Latitude 33° and 35°S from November 1988 to May 1990. MULTIFAN distinguished six cohorts in the royal red prawn population, aged at 6 mo intervals from about 1.5 to 4 yr. Most prawns were between 2 and 3 yr of age. Females and males were fully recruited at 23.1 and 21.5 mm carapace length (CL) respectively, when about 2 yr old. Females grew faster and reached larger sizes at age than males (growth coefficient, K=0.37 yr-1 and asymptotic length, L ∞=48.3 mm CL for females, and K=0.49 yr-1 and L ∞=33.5 mm CL for males). Total mortality (Z) was estimated at 1.6 and 1.2 yr-1 for females and males, respectively. Approximate values for natural mortality (M) ranged from 0.6 to 0.7 yr-1 for females, and from 0.4 to 0.8 yr-1 for males. Analysis of yield-per-recruit suggested that while the current yield could possibly be increased by decreasing the length at first capture (L c ), there seems to be little potential for an increase in yield from increased fishing effort in the area currently fished.

Life cycles, standing stocks, and drift of some Megaloptera, Ephemeroptera, and Diptera from streams in Minnesota, U.S.A.

From analyses of monthly length frequency distributions, univoltine life cycles were described for Sialis dreisbachi, Stenonema vicarium, and Dicranota sp. from stream riffles. Stream drift of immature S. dreisbachi and S. vicarium peaked near the ends of their life cycles in the spring. Drift of these two species was not related to standing stocks. Dicranota larvae exhibited negligible drift rates.

Live cycles, drift, and standing stocks of some stoneflies (Insecta: Plecoptera) from streams in Minnesota, U.S.A.

From analyses of monthly length frequency distributions of stonefly (Plecoptera) nymphs from stream riffles, two types of univoltine life cycles (Hynes 1961, classification) were observed: slow seasonal forIsoperla transmarina, Isoperla signata, Isogenoides olivaceus, andAllocapnia rickerii, and fast seasonal forProstoia similis. The Perlodidae stoneflies (Isoperla andIsogenoides) showed greatest propensities to drift near the end of their life cycles. Drift rates of the other two species of stoneflies were correlated to standing stock estimates.