Western King Prawn Penaeus Latisulcatus Research Articles

Growth and population characteristics of the Western King Prawn Penaeus latisulcatus (Kishinouye, 1896) from the southeastern Mediterranean off the Egyptian coast

Penaeus latisulcatus (Kishinouye, 1896) is considered one of the most economically important penaeid shrimp species in the Egyptian Red Sea. Recently, it appeared in the Egyptian Mediterranean catches. The present study is concerned with the estimation of growth, age and population characteristics of the non-indigenous P. latisulcatus collected between the months of July 2020 to June 2021 from the landing fishing center of Boughaz El-Maadiyah (Egyptian Mediterranean coast). A total of 2214 individuals were collected monthly. The results showed that the females to males ratio was 1:0.98. According to the Chi-square test, there was no statistically significant difference between the sexes (X2 = 0.181, df = 1, P > 0.05). The distribution of the length frequency showed that the females varied from 5.0 cm to 19.2 cm (TL) with a mean length of 11.73 ± 2.78 cm, while the males ranged from 5.3 cm to 17.1 cm (TL) with a mean length of 10.97 ± 2.06 cm. Positive allometry was detected for the total length-total weight relationship. The parameters of von Bertalanffy were L∞ = 20.56 cm, K = 0.99 yr−1 and to = −0.178 yr−1 for females, L∞ = 18.68 cm, K = 1.05 yr−1 and to = −0.172 yr−1 for males, and L∞ = 20.74 cm, K = 0.90 yr−1 and to = −0.196 yr−1 for the combined sexes. The expected age of females and males were 2.6 and 2.2 years, respectively. According to the parameters obtained, the current exploitation rate of the population of P. latisulcatus was estimated at Ecur. = 0.59. The results indicated that the population of P. latisulcatus is being highly exploited in Boughaz El-Maadiyah landing center (Egyptian Mediterranean coast). Hence, it is important to manage the P. latisulcatus shrimp resources in the studied area. Furthermore, similar studies are recommended for P. latisulcatus along the Egyptian Mediterranean coast to evaluate variations between populations in different fishing areas. Moreover, further studies are needed about the new aspects of the reproductive activity of this species as well as its aquaculture to estimate its growth rate experimentally.

Effect of sudden salinity change on Penaeus latisulcatus Kishinouye osmoregulation, ionoregulation and condition in inland saline water and potassium-fortified inland saline water

Two trials were conducted to determine the effect of sudden decrease in salinity of raw and potassium-fortified inland saline water on western king prawn Penaeus latisulcatus osmoregulation, ionoregulation and condition. Prawns were subjected to salinity decrease over 1 h from 32 to 25 ppt in the first trial and from 27 to 20 ppt in the second trial in three water types: inland saline water with potassium fortified to 100% and 80% of the marine water concentration (IS100, IS80), and raw inland saline water (ISW). In the first trial condition and ingestion rate were monitored over 19 days following salinity change. In the second trial condition, haemolymph osmo- and iono-regulation were recorded over 48 h following salinity change. In the first trial, 100% mortality was observed in ISW by day 13, with final survival 94% in IS80 and 100% in IS100. Tail muscle moisture content increased significantly (P < 0.05) over time in both trials and in all water types, suggesting loss of energy reserves. In the second trial, serum osmolality, sodium concentration and osmoregulatory capacity decreased following salinity change, stabilising by 24 h in IS100 and IS80 but continuing to decrease till 48 h in ISW, suggesting partial breakdown of osmoregulatory function in the potassium-deficient medium. Prawns were stronger regulators of divalent than monovalent cations. These trials demonstrate that potassium-deficient inland saline water requires fortification with potassium to allow prawn survival and efficient osmoregulation.

Catch equations: restoring the missing terms in the nominally generalized Baranov catch equation

Observational models for the catch of fish at age a (or size) at time t are fundamental equations in fisheries science, linking a population model with data. The well known Baranov catch equation (which assumes that fishing and natural mortalities are constant over both age and time) is a nominal basis of those most commonly used in fish stock assessment and fish population models (which assume that fishing and natural mortalities vary with both age and time). But, what should a catch equation look like, if the instantaneous rates of fishing and natural mortalities of fish of age a at time t vary with age a and time t? Without answering this question, use of those catch equations in fish stock assessment and population models renders their results uncertain. In this paper, I derive a general catch in number or in biomass equation as observational models of an age- and time-dependent model for a fish population by Taylor series expansion of, and by directly manipulating, a general catch integral, reduce it to commonly used catch equations, and compare the performance of 11 of them using data on the western king prawn Penaeus latisulcatus. I show that the nominal generalization of the Baranov catch equation misses several terms. In so doing, I derive the catch equations more accurately and restore these missing terms. Although almost all approximations overestimate the catch per recruit for older prawns, all commonly used catch equations and their extensions perform worse than theoretically sound representations of the general catch equation and their approximations. The age-specific bias of all models is <2.5, <18 and <90% for a time interval of sampling of 1, 7 and 30 days, respectively. Such large biases even for moderate values of the length of the time interval of sampling highlight a need for assessing the utility of commonly used catch equations for individual species.

Use of generalized linear models in analyzing the catch and effort data on the western king prawn Penaeus latisulcatus Kishinouye in the Gulf St. Vincent, Australia

Abstract The western king prawn Penaeus latisulcatus occurs in coastal waters off Western Australia, the Northern Territory, Queensland, New South Wales, and South Australia. In South Australia, it supports a commercial trawl fishery with an annual landed value of about AU$ 35 million. In this paper, I derive generalized linear models from an observational model of a sex-, age- and time-dependent model for a single prawn population, provide them with a firm theoretical basis, and make explicit some of their assumptions. Following an exploratory analysis by use of a generalized additive model, I use generalized linear models to analyze the commercial catch and effort data for the changes in its stock size with time, in fishing efficiency among vessels, in catch with time of day, fishing effort and area, and the effects of searching on catch. The results obtained by assuming that the catch follows independent log-gamma, log-normal, log-negative binomial, or log-Poisson distribution were similar. The relative exploitable biomass in the population immediately before the fishery was closed in 1991 was 31% of that when it was resumed in December 1993, remained at about the same level of December 1993 until 30 June 1995, slightly declined from 1 July 1995 to 30 June 1997, and was 81% of the level of December 1993 from 1 January 1998 onward. The relative instantaneous rate of fishing mortality of prawns of a particular sex and age was largely unchanged, but became less variable with time. Fishing efficiency was similar among all vessels. Normal fishing shots (using three nets) produced about three times the catch of searching shots (using only one net). Fishers learned during a sequence of shots, for prawn catch initially increased with shot number and then leveled off. A significant variation in catch with the time of day was detected, with the maximum catch occurring at 22 h. Finally, catch did not change proportionally with fishing effort; a 1% of change in effort led only to a nearly 0.9% of change in catch, so that raw catch per unit of effort decreased with fishing effort and is a biased index of the size of a prawn population. This work suggests that the current level of fishing effort cannot sustain the exploitable biomass of the population at the level of December 1993.

Use of generalized linear models in analyzing the catch and effort data on the western king prawn Penaeus latisulcatus Kishinouye in the Gulf St. Vincent, Australia

The western king prawn Penaeus latisulcatus occurs in coastal waters off Western Australia, the Northern Territory, Queensland, New South Wales, and South Australia. In South Australia, it supports a commercial trawl fishery with an annual landed value of about AU$ 35 million. In this paper, I derive generalized linear models from an observational model of a sex-, age- and time-dependent model for a single prawn population, provide them with a firm theoretical basis, and make explicit some of their assumptions. Following an exploratory analysis by use of a generalized additive model, I use generalized linear models to analyze the commercial catch and effort data for the changes in its stock size with time, in fishing efficiency among vessels, in catch with time of day, fishing effort and area, and the effects of searching on catch. The results obtained by assuming that the catch follows independent log-gamma, log-normal, log-negative binomial, or log-Poisson distribution were similar. The relative exploitable biomass in the population immediately before the fishery was closed in 1991 was 31% of that when it was resumed in December 1993, remained at about the same level of December 1993 until 30 June 1995, slightly declined from 1 July 1995 to 30 June 1997, and was 81% of the level of December 1993 from 1 January 1998 onward. The relative instantaneous rate of fishing mortality of prawns of a particular sex and age was largely unchanged, but became less variable with time. Fishing efficiency was similar among all vessels. Normal fishing shots (using three nets) produced about three times the catch of searching shots (using only one net). Fishers learned during a sequence of shots, for prawn catch initially increased with shot number and then leveled off. A significant variation in catch with the time of day was detected, with the maximum catch occurring at 22 h. Finally, catch did not change proportionally with fishing effort; a 1% of change in effort led only to a nearly 0.9% of change in catch, so that raw catch per unit of effort decreased with fishing effort and is a biased index of the size of a prawn population. This work suggests that the current level of fishing effort cannot sustain the exploitable biomass of the population at the level of December 1993.

Modelling the learning behaviour of fishers: learning more from their successes than from their failures

Learning occurs in all stages of a fishery, in the entire fishing career of a fisher, and even within a single fishing trip. It is an important aspect of fleet dynamics; failure to take it into proper account biases results of population dynamics studies and results of stock assessments. In this paper, I introduce and slightly generalise three learning models and derive a new one. I use them to analyse data on the short-term learning behaviour of all fishers as a group in the fishery of the western king prawn Penaeus latisulcatus in the Gulf St Vincent, Australia, to demonstrate their utilities. The damped periodic change inferred in fishing efficiency of all fishers as a group with time (shot number) over a fishing day in the P. latisulcatus fishery had a period of 9.44±1.06 shots and could have resulted from periodic ‘forgetting’ and forcing by good catch rates. The new learning model was used to test the hypothesis that fishers in the P. latisulcatus fishery learn more from their failures in catch rate than from their successes, or more from their successes than from their failures, or as much from their successes as from their failures. Although very limited, the data suggest that fishers as a group learn 69.03±311.52% more from their successes in good catch rates than from their failures.

Use of age- and time-dependent seasonal growth models in analysis of tag/recapture data on the western king prawn Penaeus latisulcatus in the Gulf St. Vincent, Australia

Most growth models describe a relation between an animal’s size and its age and are independent of time and time-dependent factors. However, some factors that vary with time (e.g., ambient temperature and food availability) also affect the growth of animals. Consequently, many attempts have been made to incorporate time and time-dependent factors, implicitly, in age-dependent growth models, to consider seasonal growth, biphasic growth, and the effects of tagging. But, time-dependency can render them dependent on the start of time and hence practically useless. This is because when time started is still unknown. Under what conditions are age- and time-dependent growth models independent of the start of time for them to be useful? How should their estimates of parameters be adjusted to make them useful? In this paper, we use age- and time-dependent seasonal growth models to analyse tag/recapture data on the western king prawn Penaeus latisulcatus in the Gulf St. Vincent, Australia, examine conditions under which age- and time-dependent growth models are independent of the start of time for them to be useful, and demonstrate how they should be adjusted for subsequent applications. Such analyses suggest that P. latisulcatus exhibits a strong seasonality in growth, with males’ growth cycle lagging 2 weeks behind females’. The carapace length of males grows fastest 2 weeks after the start of autumn, grows less until a full stop 2 weeks before the start of spring, shrinks until the middle spring, and resumes its positive growth for another cycle, whereas that of females grows continuously throughout the year but at a slower rate in certain months.

Estimation of Instantaneous Rates of Fishing and Natural Mortalities from Mark–Recapture Data on the Western King PrawnPenaeus latisulcatusin the Gulf St. Vincent, Australia, by Conditional Likelihood

The instantaneous rate of natural mortality is a fundamental quantity of a fish population and is often estimated through tagging experiments. In this work, we develop a simple probabilistic model that incorporates fishing mortality, natural mortality, type II tag shedding, probability of reporting, type I mortality, and type I tag shedding; derive a likelihood function for estimating model parameters; and use them to analyze a set of tagging data from a tagging experiment with the western king prawn Penaeus latisulcatus in the Gulf St. Vincent, Australia. For both males and females, the instantaneous rate of fishing or natural mortality of western king prawns above 20 mm in carapace length was not significantly affected by carapace length but varied slightly over truncated experimental tagging periods of 2,526, 2,567, and 2,933 d. Sexual differences existed in the instantaneous rate of fishing or natural mortality for each experimental tagging period. For a truncated experimental tagging period of 2,526 d, males had an 11.43% higher instantaneous rate of natural mortality and a 23.65% higher fishing mortality than females. Many other quantities could be computed by use of our model. For example, for an experimental tagging period of 2,526 d, the annual survival rate of tagged western king prawns from both fishing and natural death was 23.85 ± 0.61% for females, and 19.49 ± 0.62% for males. Finally, we explain why the instantaneous rate of natural mortality cannot be estimated reliably by use of existing models and conclude that the problem lies in our inability to measure the times of natural deaths in a population directly. The development of new technology is required to meet this challenge.

The influence of stress on oxygen consumption of rainbow trout

Two trials were conducted to determine the effect of sudden decrease in salinity of raw and potassium-fortified inland saline water on western king prawn Penaeus latisulcatus osmoregulation, ionoregulation and condition. Prawns were subjected to salinity decrease over 1 h from 32 to 25 ppt in the first trial and from 27 to 20 ppt in the second trial in three water types: inland saline water with potassium fortified to 100% and 80% of the marine water concentration (IS100, IS80), and raw inland saline water (ISW). In the first trial condition and ingestion rate were monitored over 19 days following salinity change. In the second trial condition, haemolymph osmo- and iono-regulation were recorded over 48 h following salinity change. In the first trial, 100% mortality was observed in ISW by day 13, with final survival 94% in IS80 and 100% in IS100. Tail muscle moisture content increased significantly (P < 0.05) over time in both trials and in all water types, suggesting loss of energy reserves. In the second trial, serum osmolality, sodium concentration and osmoregulatory capacity decreased following salinity change, stabilising by 24 h in IS100 and IS80 but continuing to decrease till 48 h in ISW, suggesting partial breakdown of osmoregulatory function in the potassium-deficient medium. Prawns were stronger regulators of divalent than monovalent cations. These trials demonstrate that potassium-deficient inland saline water requires fortification with potassium to allow prawn survival and efficient osmoregulation.

The identification of arsenobetaine as the sole water-soluble arsenic constituent of the tail muscle of the western king prawn Penaeus Latisulcatus

1. Samples of tail muscle of the western king prawn, Penaeus latisulcatus collected from two locations were examined separately for the presence of arsenobetaine and other arsenic compounds. 2. For both samples the aqueous extract accounted for < 97% of the total arsenic. 3. The water-soluble arsenic was present as one compound only which was isolated and identified as arsenobetaine.