Analysis of Feeding Habits and Biological Aspect of Yellow Stripe Trevally (Selaroides leptolepis) Caught at the Lekok Coast, Pasuruan, East Java

The fish population in waters can decrease due to the uncontrolled utilization of fish resources. Food is one of the determining factors for the population and condition of fish in the waters. Considering the economic and ecological importance of the yellow trevally in food webs, this research was conducted to analyze the feeding habits and biological aspects of the yellow trevally in Pesisir Lekok. This study used a descriptive data analysis with complete randomized design. The research was conducted from May to July 2023 at Pesisir Lekok, Pasuruan, East Java. The results showed that the yellow trevally is carnivorous with the dominant food found being zooplankton from the genus Microcalanus sp. with a frequency of occurrence of 41%. The highest plankton composition found in the stomach of the yellow trevally was the phytoplankton of the Aulacoseira genus, which was 22.2%. Meanwhile, the foods most preferred by the yellow trevally are Rotifera and Charophyta with an index value of +1. The biological aspect of the yellow trevally seen from the length-weight relationship shows that the growth pattern of the yellow trevally is negative allometric with a b value of 2.651. While the condition factor range average values are 1.009 – 1.027. The results of this study are expected to be the basis for efforts to support the sustainable management of fisheries resources, especially the yellow trevally in the coastal waters of Lekok.


Introduction
The potential for marine fisheries and the coastal area of Pasuruan Regency is in the form of a beach that is approximately 48 km long with generally sloping and muddy coastal conditions and overgrown with mangrove forests.The area of marine fishing exploitation reaches 112.5 square nautical miles with a sustainable potential in the Madura Strait of 49.51 thousand tonnes of fish per year.To support the capture fisheries business in Pasuruan Regency, there is a Fish Landing Base (PPI) or Fish Auction Place (TPI) in Lekok which is classified as type C with the number of fish landed 10-20 tons per day [1].
One of the highest biological resources in the Lekok coast is small pelagic fish.Yellow stripe trevally is a type of fish that belongs to the small pelagic fish category.According to Perumal et al. [2], the yellow stripe is a commercially important pelagic fish that is spread along tropical and subtropical coasts.Yellow stripe is generally found at a depth of 20 meters to a depth of 100 meters.In connection with its big role in ecology and economy, the preservation of resources for yellow trevally needs to be maintained and managed optimally and sustainably.One way to preserve fish resources is to know the eating habits and biological aspects of these fish.
Availability of food in good quantity and quality is an important factor in ensuring the population, growth, and condition of fish.Food preferences can be known through analysis of the composition of stomach contents or the relative length of the intestine in fish.Research on composition and feed habits aims to determine the role of fish in the food chain.The type of feed contained in the stomach of fish shows the relationship between ecological aspects, such as behavior, conditions, habitat adaptation, and interactions between species which play an important role in ecosystem-based fisheries management.Feeding habits include the composition of the types of organisms that have been ingested by fish, including food sources in the waters, such as sediments, benthic organisms, plankton, and fish larvae [3].Fish feed habits can be determined based on the maximum percentage of types of feed found in the intestines or stomach of fish.Fish are classified as herbivores if their diet consists of aquatic plants, carnivores if their diet consists of animal ingredients, and omnivores if they eat more than one group of organisms, such as plankton, nekton, or detritus [4].
The relationship between length, weight, and condition factor are two important parameters in the study of biological aspects that provide important information related to the physiological state of fish.The condition factor is the physiological condition of fish which is indirectly influenced by intrinsic and extrinsic factors to show the obesity rate in fish [2].While the long-weight relationship describes the growth of fish and is used in estimating fish stocks.The long-weight parameters (a and b) are useful in fisheries specifically for estimating individual weights, calculating condition factors, and comparing environmental conditions and different fish habitats.Condition factors and fish length can be influenced by several factors, one of which is the availability of food sources in the aquatic environment.In addition, it can also be influenced by age, sex, and level of maturity of the gonads [5].
Based on the description above, it is necessary to research to analyze the feeding habits and biological aspects of the yellow stripe trevally which include the long-weight relationship and condition factors to create optimal and sustainable management of fisheries resources in the Lekok coast, Pasuruan Regency, East Java.

Research Method
This study used a descriptive data analysis with complete randomized design.Determination of sampling locations by purposive sampling based on migration patterns and distribution of yellow trevally fish caught in Lekok waters, Pasuruan Regency.Three sampling locations are considered to represent the general condition of Lekok waters.Fish sampling was carried out 3 times within 1 month for 3 months.The yellow trevally fish are caught by fishermen in the evening and at night using a fixed lift net.
The fish samples obtained were then measured for length using a caliper and their weight using a digital scale to analyze growth patterns and condition factors.Furthermore, dissection was carried out on the fish's digestion using a dissecting tool.The stomach of the yellow trevally was preserved by adding 10% formalin solution to the sample bottle and stored in a cool box filled with ice cubes for further observation in the laboratory.Analysis of the fish stomach aims to see the eating habits of the yellow trevally including the frequency of occurrence, calculation of the type of food composition, and determine the fish food choice index.
Observations in the Laboratory are observations of fish-eating habits that are carried out by observing the stomach contents of fish using microscope with key identification book.Before the observation, the stomach was first cleaned of formalin with running water and dried using a tissue.Then the stomach is split open and the contents are removed, then the contents are separated according to the type of food using a microscope.

Research Variables
The research variables were frequency occurrence, plankton species composition in the stomach, index of food selection, length-weight relationship, condition factors, and water quality parameters as supporting data including temperature, pH, dissolved oxygen, and salinity.

Data Analysis 2.4.1 Analysis of Fish Stomach Contents a. Frequency of occurrence
The percentage frequency of occurrence (Oi) is expressed by counting the total amount of one type of food per number of stomachs that are filled [6].The frequency of occurrence is calculated using the formula: Information: Oi = percentage frequency of occurrence of these foods (%) Ni = number of occurrences of food to i I = the number of stomachs containing food b.Calculation of the plankton species composition in the stomach The plankton composition in the fish stomach can be calculated using the formula [7]: Selection of certain types of food is measured using the preference index [8], with the following formula: The condition factor (K) is calculated based on the length and weight of the fish using the formula [9]: = coefesien and regression

Result and Discussions
An analysis of feeding habits and biological aspects was carried out on 31 yellow trevally fish caught using a fixed net fishing gear in the coastal waters of Lekok, Pasuruan Regency.The results of gastric examination of all fish samples caught at 3 stations showed that most of them were filled with food, except for 9 stomachs which were found to be empty or where food was not found.This can happen because at the time of catching, the fish may not have consumed the food or the food has been digested properly so that there are no food scraps left in the stomach.This is to the statement of Anugerah et al. [10], that some fish have a high level of food digestibility so that when fish are caught the fish's stomach is empty.

Frequency of Occurrence
Frequency of occurrence (Oi) is a method that describes the intensity of each type of food found in the stomach of a fish.Analysis of the gastric contents of the yellow trevally caught in Lekok waters found 2 types of food, namely phytoplankton and zooplankton.Phytoplankton and zooplankton found in the stomach of the yellow trevally consist of several genera which are presented in Table 1 below.Based on the results of the calculation of the frequency of occurrence, the food that has the highest value in the stomach of the yellow trevally is zooplankton with the most common genus, namely Microcalanus sp. of the phylum Arthropoda.This proves that the yellow trevally has a feeding habit as a carnivorous fish.According to Sriyanti et al. [11], based on the composition of the types of food, the yellow trevally fish is classified as a carnivorous fish because it predominantly eats zooplankton.Carnivorous fish generally have a shorter gut length than their body length.Therefore, carnivorous fish do not take long to digest their food.
There are 6 types of food composition identified in the stomach of yellow trevally, consisting of Chlorophyta phylum with an incidence frequency of 2%, Dinophyta 2%, Charophyta 5%, Bacillariophyta 41%, Rotifera 5% and Arthropods 45% (Figure 2).This is by the research of Bintoro et al. [12], that the composition of the food for small pelagic fish consists of the Phyla Arthropoda, Ochrophyta, Chlorophyta, Bacillariophyta, Molluscs, Protozoa, Cyanophyta, Cnidaria, and Ciliophora.While the highest frequency index consists of the Arthropod phylum with a value of > 65%.Differences in the number of food organisms eaten by fish occur due to differences in the distribution of organisms in each region.In addition, factors that affect organisms' preference for food include the availability of food, the choice factor of the fish itself, and aquatic environmental factors [13].

Food Composition in the Stomach of Yellow Stripe Trevally
Based on the results of observing the composition of food species in the stomach of yellow trevally caught in Lekok waters, Pasuruan Regency, it was found that the food with the largest composition was phytoplankton with the highest relative abundance, namely the Genus Aulaceseira sp.22.2% and Schizomenis 19.84%.Then followed by zooplankton with the highest relative abundance, namely the Genus Microcalanus sp. by 7.94%.This could be due to the higher abundance of phytoplankton in the water when compared to zooplankton.Phytoplankton in the waters are more abundant than zooplankton.In addition, the yellow trevally is a type of pelagic fish, which is dominated by phytoplankton in this zone.According to Pratiwi et al. [14], the availability of food in the waters can slowly affect the composition of food in the stomach organs.The food consumed can be assumed as a substitute for food or the only food that can be eaten while the main food is not available.This tends to change the behavior of food from zooplankton to phytoplankton because of its availability in the waters.The results of the composition of the food contained in the stomach of the yellowstripe can be seen in Table 2 and Figure 3.

Index of Food Selection
The food selection index is a comparison between the fish-feed organisms found in the stomach and the fish-feed organisms found in the waters.The fish food selection index aims to determine the types of food that are liked and disliked by fish, where a positive value indicates the type of food that is preferred and a negative value indicates the type of food that is not preferred by the yellow trevally.The results of the selection index calculation show that the types of food preferred by the yellow trevally are rotifers and charophyta with a choice index value of 1.Meanwhile, dinoflagellates have a value of 0 which indicates that there is no fish selection for the feed.The food selection index of yellowstripe trevally for food types can be seen in Table 3.Based on the results of the study, Rotifers are not found in waters, while they are found in the stomach of the yellow trevally, this is due to the nature of the fish that move freely and the behavior of fish that live in flowing waters to swim more actively, so that the movement of these fish is wider in search of food [15].According to Effendie [16], the assessment of fish preferences for food is very relative.Several factors that can influence include the spread of fish organisms, food availability, fish choice of food, and physical factors that affect the waters.

Length-Weight Relationship of Yellow stripe trevally
Based on the results of the study, the number of fish caught during the study was 31 individuals with an average length of 18.2 cm and an average weight of 72.2 grams.The results of the regression analysis and the relationship between the length and weight of the yellow trellis produce a regression equation that is y = 0.0219 x -2.7561 with a determination value of 0.95 which means that 95% of the weight gain is due to the increase in length, while the other 5% is caused by other unknown factors.The correlation coefficient value was 0.97 which indicated that there was a very strong relationship between length gain and weight of yellow trevally in Lekok waters.The results of the analysis of the long-weight relationship obtained results with a coefficient b of 2.651 which has a negative allometric growth pattern, meaning that the increase in length of the yellow trevally is faster when compared to the increase in body weight.The results of the regression of growth in length and weight of the yellow trevally can be seen in Figure 4.
Negative allometric growth is intended for fish that have a value of b<3 which means that this species has a relatively slow speed and the growth rate tends to be thinner [17].The b coefficient is influenced by fish behavior, in which active swimming fish show a lower b value than passive swimming fish.This relates to the allocation of energy expended for its movement and growth [18].Fish growth can be influenced by several factors, both internal and external factors.Factors that generally affect the growth of fish can be genetic, sex, age, and fish diseases.Meanwhile, the main external factors that affect growth are food and the aquatic environment [19].

Conditions Factor of Yellow Stripe Trevally
Condition factors were calculated to assess general fish health, productivity, and physiological conditions of fish populations based on fish length and weight data.The results of calculations and the average condition factor for yellow trevally can be seen in Table 4.The results of calculating the condition factor during the study ranged from 0.674 -1.404.The lowest condition factor value was found in a fish measuring 12 cm with a body weight of 24 grams and the highest condition factor was found in a fish measuring 16 cm with a body weight of 50 grams.Differences in condition factor values are caused by variations in the range of length and weight, these variations in size can affect the size of fish that will spawn.According to Shasia et al. [20], spawning can be one of the causes of changes in fish condition factor values.In addition, differences in condition factor values are influenced by population density, diet, gender, and age.
Based on the average of the condition factor values, the yellow trevally is included in the fat fish category.This is to the statement of Perdana et al. [21], that fish that have a condition factor value of 0 -0.49have a very flat body shape, a value of 0.50 -0.99 has a flat body shape, a value of 1.0 has a medium body shape, a value of 1.01 -1.50 has a fat body shape and a condition factor value 1.51 -2.0 has a very fat body shape.This is to the statement of Getso et al. [22], that condition factors that have a value ≥ 1 are within the recommended normal range.This shows the level of good feeding and good environmental conditions.Fish with low condition factor values indicate that fish are in a bad environment and have insufficient nutrition.According to Wahyudewantoro and Haryono [23], a higher value of the condition factor indicates a match between the fish and its environment.

Water Quality
The quality of the aquatic environment is one of the important factors affecting the life of the biota in it.Good water quality is very supportive of fish growth and determines the availability of food in the waters.The results of water quality measurements on the Lekok Coast can be seen in Table 5.Based on the results of measuring water quality in the Lekok Coastal area, it was found that several parameters measured still met the quality standards for fish growth based on Government Regulation No. 22 of 2021.The growth of fish in certain waters is influenced by environmental factors, including the size of the food eaten, the size of the fish, the type of food eaten, as well as the quality of the environment, and IOP Publishing doi:10.1088/1755-1315/1328/1/01200111 the condition of the fish.Therefore, habitat and food are important factors for the survival of aquatic organisms because habitat and food are interconnected with each other and each habitat has an abundance of food that varies depending on the physical and chemical factors of the waters [24].

Conclusion
The conclusion obtained from this study is that the yellow trevally caught in Lekok waters belongs to the carnivorous fish species with the highest frequency of occurrence, namely Microcalanus sp.As well as the preferred index of food choices for yellow trevally fish, namely Rotifera and Charophyta.Yellow trevally is negative allometric and the condition factor is included in the fat category.

2 .
Material and methods 2.1 Time and Place of Research Sampling of yellow trevally fish was carried out in coastal waters of Lekok, Pasuruan Regency, East Java Province from May to July 2023 and identification of plankton in fish stomachs was carried out at the Hydrobiology Laboratory, Faculty of Fisheries and Marine Sciences, Brawijaya University.The research location can be seen in Figure 1.

Figure 1 .
Figure 1.Sampling site of this research the index of food selection ri = relative number of the type of eaten organism pi = relative number of the type organism within the waters 2.4.2Growth Analysis a. Length-weight relationship The length-weight relationship follows the cubic law, that the weight of the fish is the cube of its length [9] with the following formula: ܹ = ‫ܮܽ‬ ‫݃ܮ‬ ܹ = log ܽ + ܾ log ‫ܮ‬ Information: W = weight of the fish (gram) L = length of the fish (cm) a = linear regression intercept b = regression koefesien b.Factor conditions

Figure 2 .
Figure 2. Frequency occurrence of Yellow stripe trevally

Figure 3 .
Figure 3. Food composition in the stomach of yellow stripe trevally.

Figure 4 .
Figure 4. Graph of the length-weight relationship of yellow stripe trevally

Table 1 .
Types of yellow stripe trevally food

Table 2 .
Food composition in the stomach of yellow stripe trevally

Table 3 .
Index of food selection for yellow stripe trevally for a type of food Phylum

Table 4 .
The condition factor for the yellow stripe trevally in the Lekok Coast

Table 5 .
Results of water quality measurements