Fish Length Research Articles

Сведения о росте и возрасте арктического шлемоносного бычка Gymnocanthus tricuspis (Reinhardt, 1830) в Карском море

This article provides data on size-age composition and growth rate of arctic staghorn sculpin Gymnocanthus tricuspis (Reinhardt, 1830) in the Kara Sea. Sculpins aged from 1+ to 7+ years, total length (TL) 4.5–19.5 cm long, and weighing 0.8–111.0 g were registered in catches. It is known that during the first three years of life, body sizes of males and females of this species are comparable, but from the fourth year onwards, females grow much faster; that’s the reason why length and weight of fish with the same age may be significantly different. Individuals of G. tricuspis with a TL 9.0–11.0 сm and age 4+ dominated.

The asymmetry in the sagitta of four mugilid species obtained from Köyceğiz Lagoon, Aegean Sea, Turkey.

Otolith features such as size and weight were analysed in 656 fish specimens of Chelon auratus, Chelon labrosus, Chelon saliens and Mugil cephalus collected from the Köyceğiz Lagoon System, Aegean Sea, southwest Turkey. The aim was to calculate the asymmetry value of the otolith length (OL), otolith width (OW) and otolith weight (OWe). The asymmetry value of OL was greater than that of OW and OWe. The asymmetry value of the three otolith parameters increased with an increase in the fish's length. The probable cause of asymmetry in the otolith parameters investigated has been determined relative to the variability in growth prompted by ecological impact linked with the disparity in water temperature, salinity, depth and contaminants existing in the Köyceğiz Lagoon System.

Comparative bilateral asymmetry of six Barbus species collected from the rivers in western Anatolia, Republic of Türkiye

ABSTRACT The bilateral asymmetry was analysed on 259 fish specimens comprising six Barbus species collected in June-August 2010 from rivers in western Anatolia. The goals of this study are: (1) to check for the levels of bilateral asymmetry amid the ten morphological features of the six Barbus species and (2) to compare the levels of this asymmetry among the ten localities in western Anatolia. The possibility of applied investigations using bilateral asymmetry and fishes as an indicator of the health of the freshwater systems was also conducted. Statistical analyses have shown that the ten morphological traits chosen for this study exhibit variable levels of bilateral asymmetry in the six Barbus species collected from the ten localities studied. The asymmetry value was highest for snout length and lowest for the prepectoral fin length observed in B. pergamonensis. An increasing tendency in asymmetry levels was exhibited for each of the ten morphological traits in the fish length groups selected for each Barbus species assessed. The result of the individuals being right-handed or left-handed has shown that specific morphological characteristics are either dextral or sinistral or showed no bilateral asymmetry in different Barbus species studied.

Factors influencing the home range of freshwater fishes

AbstractInitial investigations of home range for freshwater fish noted that it scaled allometrically, with additional studies having linked home range to variations in water body size. Here, we revisit the analysis of factors influencing freshwater fish home range sizes using an expanded dataset incorporating more recent telemetry data and a meta‐analysis approach to evaluate the influence of fish length, water body size, trophic guild and latitude on the home range size of fishes in lotic and lentic systems. With the expanded data set we reaffirm that length has a significant effect on the home range size in both lentic and lotic environments, with the effect of length being more pronounced in lotic environments. Similarly, we determined water body size also significantly influences home range size and is the key determinant of home range size in both lentic and lotic environments. We also demonstrate the importance of trophic guild and latitude as determinants of home range in lentic and lotic environments. The factors influencing home range size in both environments were common (i.e. fish length, water body size, trophic guild and latitude), but varied in importance weight between the environments. The results of this study help illuminate the weight of importance of factors influencing the home range of freshwater fishes and provide useful information for conservation and environmental management planning purposes.

Validation of the Use of Otoliths to Estimate Age and Growth of Larval Lake Whitefish, Coregonus clupeaformis

Understanding drivers of recruitment variation in fish populations requires research conducted on early life stages. Examination of fish otoliths provides useful information for estimating hatching dates, growth, and survival rates of larvae and for investigating the relationship between early life stage phenology and variation in environmental factors such as climate and food availability. In the Laurentian (i.e., North American) Great Lakes, significant reductions in the number of young (ages 1–4 years) lake whitefish (Coregonus clupeaformis) recruiting into the population and commercial fishery have raised questions about factors affecting growth and survival of the larval life stage. Here, we investigate the utility of using otoliths to estimate the age and growth of larval lake whitefish. We raised offspring of wild-caught parents from Lake Simcoe (Ontario, Canada) in a hatchery environment and analyzed otoliths of these known age fish for 75 days posthatch. We further examined otoliths of wild-sampled larvae and age 0 lake whitefish from Lake Huron. We found a strong linear relationship between known age and number of postcheck increments on the otolith and between growth of the otolith and fish length. Increments formed at nearly 1 (0.9) per day beginning at day 20 after hatch. Check and subsequent increment formation was associated with disappearance of the yolk sac. Wild fish had more prominent checkmarks and grew slower than hatchery fish. Thus, otolith analysis represents a promising tool to examine dynamics of early life stages of lake whitefish, although further research is required on the effects of environmental conditions on otolith microstructure.

The Importance of Habitat and Lake Morphometry for the Summer Diet Choice of Landlocked Arctic Char in Two West Greenland Lakes

Arctic char (Salvelinus alpinus) is a top predator and the most widespread fish in Arctic lakes. The presence of Arctic char affects the predator–prey dynamics of the key species in the food webs in these lakes. This study sought to elucidate the effects of habitat (littoral, pelagic, or profundal) and lake morphometry on the trophic position of this char in the food web. Using stomach content and stable isotope analyses, we investigated the effect of fish length, habitat, and time (individual survey years: 2008, 2013, 2018, and 2019) on the dietary niches of landlocked Arctic char populations during summer in two west Greenland lakes: Badesø (area 0.8 km2, mean depth 9.2 m) and Langesø (area 0.3 km2, mean depth 5.0 m). The small char (<20 cm fork length) in Badesø generally foraged less littoral macroinvertebrates than those from Langesø. The large chars were mainly piscivorous in both lakes. In Badesø, there was a shift from relying on littoral to pelagic invertebrates by the small char from 2008–2013 to 2018–2019. The proportionally larger size of the littoral habitat in the smaller Langesø led to an increased reliance on littoral-derived macroinvertebrates in the diet of the small char, more so than in the larger Badesø, where the predominant reliance was on pelagic sources.

Morphological traits for allometric scaling of the European Sea Bass Dicentrarchus labrax (Linnaeus, 1758) from Southern Portugal population.

The present study aimed to determine the allometric scaling among a selection of morphological traits in European sea bass (Dicentrarchus labrax) to estimate fish body weight. A set of morphological traits (fish body weight, length, height, and width) were directly measured in 146 fish of a recirculating aquaculture system, with body weights ranging from 17.11 to 652.21 g. In addition, a collection of digital imagery of each anesthetized fish from the side and top views were used to estimate other traits (indirect measures). Multiple regression analysis and regression coefficients were calculated using all possible combinations of biometric data (predictors) to estimate fish body weight, applying different numerical fitting models (linear, log-linear, quadratic, exponential). The results showed that the best combination of traits for estimating fish body weight were fish body width, length and height, collected from direct measure (R2 = 0.995), for a log-linear model fitting, which revealed more accurate determinations than the most commonly used length-weight relationship. Nevertheless, other combinations of morphological traits and fitting models were also found to be suitable in successfully predict fish body weight, with variability ranging between 92.5% and 98.5%. For indirect measures, the best predictor was a combination of traits from top view (width, eye distance and area without fins) fitted with a log-linear function. These results comprise a relevant baseline in supporting the high potential of noninvasive methods to accurately follow the growth of European sea bass juveniles, recurring to imagery analysis of anesthetized fish. It has major potential applications in feeding consumption trials and fish growth models, as it allows for continuously following up fish growth under different experimental conditions without therein distress derived from manipulation.

New record of Chromis weberi (Actinopterygii: Ovalentaria: Pomacentridae) from Jeju Island, southern Korea

Discovering tropical marine species outside of their distribution limits is important for evaluating the impact of climate change on marine ecosystems. One specimen (31.6 mm standard length) of a tropical fish, Chromis weberi Fowler et Bean, 1928, representing the family Pomacentridae, was first recorded from Jeju Island, Korea, on 8 December 2021. It was characterized by black posterior margins of the preopercle and opercle and black upper and lower lobes of the caudal fin. A specimen of this species collected from Munseom was distinguished from Chromis xanthura (Bleeker, 1854) based on distinct differences in the tips of the upper and lower caudal fin lobes, which are not black in C. xanthura. In addition, C. weberi was easily distinguished from the other four species in the genus Chromis, by the mitochondrial DNA cytochrome c oxidase subunit I gene sequence (345 bp), with genetic distances ranging from 0.130 to 0.252. This study documents the first record of C. weberi in temperate Korean waters, implying a poleward range expansion for this species. The Korean name ‘geom-eun-jeom-ggo-ri-ja-ri-dom’ has been proposed for C. weberi.

Fish Size Structure as an Indicator of Fish Diversity: A Study of 40 Lakes in Türkiye

Body size is a master trait in aquatic ecosystems to complement traditional taxonomic diversity measures. Based on a dataset of fish communities from 40 Turkish lakes covering a wide environmental gradient and continental to dry cold steppe to Mediterranean climates, we elucidated the key variables controlling size diversity, geometric mean length and number of size classes in the fish community. We further examined how these three size measures were related to species diversity and species richness. A GLM analysis revealed that both size diversity and the number of sizes were strongly related to taxonomic diversity and richness. Furthermore, fish size diversity decreased with decreasing annual precipitation, while the number of size classes increased with increasing lake area but decreased with increasing salinity. The geometric mean length of fish decreased with total nitrogen and increased with altitude. The inter-relatedness between the number of size classes and lake area suggests an increase in fish niches with increasing ecosystem size, while fish are smaller and have fewer size classes in lakes with higher salinity. We conclude that size measures provide valuable integrating information on lake fish diversity; thus, they may complement, but not replace, more traditional taxonomic fish measures.

Generalised deep learning model for semi-automated length measurement of fish in stereo-BRUVS

Assessing the health of fish populations relies on determining the length of fish in sample species subsets, in conjunction with other key ecosystem markers; thereby, inferring overall health of communities. Despite attempts to use artificial intelligence (AI) to measure fish, most measurement remains a manual process, often necessitating fish being removed from the water. Overcoming this limitation and potentially harmful intervention by measuring fish without disturbance in their natural habitat would greatly enhance and expedite the process. Stereo baited remote underwater video systems (stereo-BRUVS) are widely used as a non-invasive, stressless method for manually counting and measuring fish in aquaculture, fisheries and conservation management. However, the application of deep learning (DL) to stereo-BRUVS image processing is showing encouraging progress towards replacing the manual and labour-intensive task of precisely locating the heads and tails of fish with computer-vision-based algorithms. Here, we present a generalised, semi-automated method for measuring the length of fish using DL with near-human accuracy for numerous species of fish. Additionally, we combine the DL method with a highly precise stereo-BRUVS calibration method, which uses calibration cubes to ensure precision within a few millimetres in calculated lengths. In a human versus DL comparison of accuracy, we show that, although DL commonly slightly over-estimates or under-estimates length, with enough repeated measurements, the two values average and converge to the same length, demonstrated by a Pearson correlation coefficient (r) of 0.99 for n=3954 measurement in ‘out-of-sample’ test data. We demonstrate, through the inclusion of visual examples of stereo-BRUVS scenes, the accuracy of this approach. The head-to-tail measurement method presented here builds on, and advances, previously published object detection for stereo-BRUVS. Furthermore, by replacing the manual process of four careful mouse clicks on the screen to precisely locate the head and tail of a fish in two images, with two fast clicks anywhere on that fish in those two images, a significant reduction in image processing and analysis time is expected. By reducing analysis times, more images can be processed; thereby, increasing the amount of data available for environmental reporting and decision making.

Condition factor and health inference of garua bachcha Clupisoma garua in the river Old Brahmaputra, north-eastern Bangladesh

A twelve-month study over a year was conducted from Januaryto December 2016 to determine condition factor and health condition of garua bachcha, Clupisoma garua (Hamilton, 1822) in the river Old Brahmaputra, Bangladesh.Condition factor of an individual fish was estimated as the ratio of the parameter, a in length-weight relationship (LWR), (W=aLb), and a' in a'=W/Lb, where, L and W are length and weight of the individual fish respectively. The study calculated condition factors in four ways. Firstly,it was determined according to length classes of each month with corresponding monthly LWR, secondly, according to length classes of each month with LWR of pooled data over the study period. The third and final ways wereemployed according to length classes with LWR of pooled data over the study period, and according to monthly mean length and mean weight data with LWR of pooled data over the study period respectively. Garua bachcha were not in ideal health condition irrespective of length classes and months under any of above mentioned methods of calculation, rather they were either lean or plump during study period. Monthly health conditions did not reveal any definite trend.Monthly sample-wise a'/a values explained that fish individuals were lean in January, while they attained plump health in other months from February to December.

Species independence of eye lens dimensions in teleosts and elasmobranchs.

The vertebrate eye lens grows incrementally, adding layers of elongated, tightly packed lens fiber cells at the outer margin of the lens. With subsequent growth, previously-deposited fiber cells degrade, leaving a region of fully denucleated and organelle-free cells which are responsible for the high transparency and low light scattering characteristics of the lens. The objective of this study was to determine if the horizon separating the gelatinous outer cortex of the lens from its hardened interior occurred at a consistent location within the lens of several teleost and elasmobranch fish species, and could be linked to fiber cell morphology or function. A fixed ratio of 0.69±0.01 of hardened eye lens diameter (HD) to overall eye lens diameter (LD) was observed in a broad size range of Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), thorny skate (Amblyraja radiata) and round ray (Rajella fyllae). The location of the hardened lens horizon was similar to that reported for optical plasticity and spherical aberration, but not that of fiber cell denucleation, suggesting that fiber cell dehydration continues after the loss of internal organelles. Our findings support a previous suggestion that the maintenance of optical quality during fish eye lens growth requires a precisely-fixed HD:LD ratio, while the ubiquity of a fixed ratio across fish taxa may suggest that many fish species possess a common refractive index profile. The linear relationship between HD and fish length should allow fish length to be backcalculated from the diameter of the isolated lens core, thus aiding research using isotope ratios of lens laminae or inner cores to reconstruct early life history events.

Internal injuries in marine fishes caught in beam trawls using electrical versus mechanical stimulations

Abstract To improve the ecological and economic sustainability in the Dutch beam trawl fishery, tickler chains were replaced by electrical pulse stimulation to drive common sole (Solea solea) out of the seabed. Because electrical stimulation may cause internal injuries, we quantified this risk by sampling fish species from commercial beam trawlers and recording spinal injuries and haemorrhages from X-radiographs and autopsy. To distinguish mechanically-induced and electrical-pulse-induced injuries, we compared injuries in ten species sampled from pulse (PUL) and tickler-chain (TCK) trawlers and four species sampled from PUL trawlers with the stimulus switched on or off. Co-occurrence of a major spinal injury and major haemorrhage at the same location was only observed in PUL samples, and were frequently (40%) observed in Atlantic cod (Gadus morhua) and in low numbers (0–2%) in whiting (Merlangius merlangus), grey gurnard (Eutrigla gurnardus), and greater sandeel (Hyperoplus lanceolatus), but not in flatfishes and other species. In cod, injury occurrence correlated with fish length, with lower probabilities for small fish. Major spinal injury or major haemorrhage occurrence in PUL (range: <1–16%) was lower than in TCK (range: <1–42%) in eight of the ten species studied. Population level consequences of pulse-induced injuries are considered negligible.

Fish muscle mercury concentration and bioaccumulation fluctuate year-round - Insights from cyprinid and percid fishes in a humic boreal lake

Boreal lakes demonstrate pronounced seasonality, where the warm open-water season and subsequent cold and ice-covered season dominate natural cycles. While fish muscle total mercury concentration (mg/kg) [THg] is well documented in open-water summer months, there is limited knowledge on the ice-covered winter and spring mercury dynamics in fish from various foraging and thermal guilds. This year-round study tested how seasonality influences [THg] and its bioaccumulation in three percids, perch (Perca fluviatilis), pikeperch (Sander lucioperca), ruffe (Gymnocephalus cernua), and three cyprinids, roach (Rutilus rutilus), bleak (Alburnus alburnus), and bream (Abramis brama) in deep boreal mesotrophic Lake Pääjärvi, southern Finland. Fish were sampled and [THg] was quantified in the dorsal muscle during four seasons in this humic lake. Bioaccumulation regression slopes (mean ± STD, 0.039 ± 0.030, range 0.013–0.114) between [THg] and fish length were steepest during and after spawning and shallowest during autumn and winter for all species. Fish [THg] was significantly higher in the winter-spring than summer-autumn in all percids, however, not in cyprinids. The lowest [THg] was observed in summer and autumn, likely due to recovery from spring spawning, somatic growth and lipid accumulation. Fish [THg] was best described by multiple regression models (R2adj: 52–76%) which included total length and varying combinations of seasonally changing environmental (water temperature, total carbon, total nitrogen, and oxygen saturation) and biotic factors (gonadosomatic index, and sex) in all species. The seasonal variation in [THg] and bioaccumulation slopes across multiple species suggests a need for standardized sampling seasons in long-term monitoring to avoid any seasonality bias. From the fisheries and fish consumption perspective in seasonally ice-covered lakes, monitoring of both winter-spring and summer-autumn would improve knowledge of [THg] variation in fish muscle.

Overlapping scales: Bias and variability in Alaska Chinook salmon age estimates

Alaska’s Chinook salmon (Oncorhynchus tshawytscha) populations have declined in size at age and age at maturity over the past 30 years, and productivity and adult abundance have decreased during the past decade. Chinook salmon scale age data are used to understand population demography, but methods for scale age estimation may have changed over time and may differ across the state. To begin addressing this, we examined variability and bias associated with age estimates from 10,200 scales, one scale per fish, from five Chinook salmon stocks (Stikine, Copper, Karluk, Nushagak, and Kuskokwim rivers), 1980–2015. This set of scales had an original assigned age, and, from this study, ages estimated by 10 participants (readers) with a range of experience. Variability was assessed using standard deviation (SD) of reader age estimations. We compared SD among stocks, marine ages, time periods (1980–1992, 1993–2005, and 2006–2015), and reader experience. Standard deviation increased by 0.014 for each 10.0 mm difference in fish length from expected length at age. Standard deviation differed among marine ages, with marine age-1 and age-5 scales having 155% and 188% of the variability of marine age-3 scales. Standard deviation did not differ among stocks or time periods. Reader bias was the percentage of scales over or underestimated relative to the median age assignment of 10 readers (the best approximation to known age). Reader bias differed among marine ages with the oldest ages tending to be overestimated and the youngest ages tending to be underestimated. Reader bias decreased with reader experience and was not different among stocks, time periods, or between familiar (those previously examined by a reader) and unfamiliar (new to the reader) stocks. Original ages were underestimated by 3% and overestimated by 9%. Bias in original ages did not differ among stocks, time periods, or marine ages. We provide recommendations, based on our results, for improving the quality of Chinook salmon scale age estimates in the future.

Intra-specific correlations between fatty acids and morphological traits are consistent across fish species

We explored intraspecific relationships between biochemical and morphometric traits among sixteen fish species from the Canadian waters of the Laurentian Great Lakes. We focused on hypotheses linking two morphometric descriptors (fish length and condition factor, CF, the latter derived from species-specific allometric-growth equations) to lipid content and polyunsaturated fatty acid (PUFA) composition of dorsal muscle tissue. Each population from each of the lakes was assumed to display different relationships. All correlations were better represented by linear than non-linear relationships. Interspecific and among lakes differences accounted for most of the registered variability of fatty acid (FA) composition. Once these two covariates were parsed out, there was a discernible intraspecific coupling between fish length, CF, and fish biochemical traits, including positive correlations with muscle lipid and PUFA composition. The sign of the correlations was consistent among different populations, aligned with the theoretical expectations, and with interspecific trait correlations. However, for some species, correlations could be positive in one lake but negative in another, suggesting that local environmental variations could affect biochemical rates. We also found three trends associated with the rate at which different fatty acids accumulate in fish muscle tissue that are potentially related to food availability. These relationships between CF and FA composition provide a promising starting point to establish efficient, cost-effective, field-based estimates of essential FA descriptors. In this vein, we present a user-friendly application for the estimation of lipid content and PUFA composition, based solely on weight and length, that any angler and/or citizen-science participant can easily obtain.

Digenetic Parasite Diversity of the Coastal Trevally Fish, Carangoides caeruleopinnatus: Factors Influencing Parasitism

Background: Carangidae is a family of ray-finned fish within the order Carangiformes which are invaded by different parasite species and the rate of parasitism changed regarding different factors. This study aimed to provide information about the relationship between fish size and sex on the parasites that infect fish within the family Carangidae in Saudi Arabia. Methods: A total of 90 Carangoides caeruleopinnatus specimens were collected from the Red Sea. The size of the fish was taken in grams (for weights) and centimeters (for lengths), respectively, as well as fish sex was determined. Fish organs were examined for parasitic infection. Result: There is a relationship between the length, weight and sex of fish hosts on the incidence of parasitic infection in the examined fish. Larger fish size is heavily parasitized than smaller ones which provide a greater surface for infection. In addition, the mean weight of uninfected samples was considerably higher than infected which suggested a weight loss because of parasitic infection. Parasitism in fish has been reported to be sex-biased, with males suffering greater susceptibility than female fish. This study reflects the rate of parasitism in the coastal trevally, Carangoides caeruleopinnatus, concerning fish length as well as their sex.

Performance and gut microbiota of catfish (Clarias gariepinus) fed powdered Moringa oleifera leave as additive (Probiotics)

The antimicrobial activity of powdered Moringa oleifera leaves on the performance of Clarias gariepinus juveniles was investigated. A total of 180 C. gariepinus hatchery-bred juveniles were obtained, acclimated in a 4 × 4 × 3 feet concrete tank, and fed adlib with 1.5 mm Coppens for one week. Initial mean weight (g) and length (cm) of sample fish were measured and randomly distributed in triplicates of 15 fish/tank into twelve concrete tanks of dimension 4 × 4 × 3 feet (T1A-C – T4A-C). Four treatment diets were formulated, by adding graded levels of powdered M. oleifera leaf to the fish feed, using starch as binder. T1 (control) had no moringa inclusion (control), while T2, T3, and T4 respectively had 5 g, 10 g, and 15 g/kg inclusion. Length (cm) and weight (g) of fish were measured fortnightly, while haematology and serum profile, bacteria in the gut were collected at the end of the study. One-way Analysis of Variance (ANOVA) was used to analyze the data, and Duncan's multiple range test was employed for mean separation. Results revealed a significantly higher growth response in T3 compared to other treatments (P < 0.05). Haematological and seriological profile showed a boost in immunity of fish fed with the additive. Bacterial load in the fish gut was significantly reduced (P < 0.05) as inclusion of additive increased. Therefore, for optimum fish production addition of 10g of M. oleifera/Kg of feed is recommended, as it gave the best result in terms of growth (P < 0.05).

A compact underwater stereo vision system for measuring fish

In the context of aquaculture, fish length is a key parameter to assess fish stocks, essential for feeding regime and contributes for decisions at several production levels. However, taking length measurements is a cumbersome task that, when applied to living individuals, can induce considerable stress, increasing the risk of damage or hindering their growth. Computer vision is one of the most used non-contact tools to overcome this issue, being fast, consistent and repeatable. However, its use in aquatic environments is limited by the high cost, the difficulty of calibrating the system in underwater conditions and the complexity of implementation. This paper proposes a low-cost easy-to-use vision system that can take measurements on live fish in aquatic conditions, without the need for a special calibration or a demanding in-water calibration service. The present work implemented a compact stereo vision system and developed a method that estimates the correct length of fish, based on the variation of the angle of incidence of the light rays in the water. Given some structural conditions such as a short baseline, the system is able to measure fish with an error of less than 1%. The short baseline allows to have a compact system and reduces the effect of water refraction on the 3D reconstruction. A set of experiments were performed with real fish, working robustly for a set of orientations of the fish (even when the caudal fin and snout are on different distances to the cameras).

Active acoustic surveys reveal coastal fish community resistance to an environmental perturbation in South Florida.

Coastal fish communities are under increasing levels of stress associated with climate variation and anthropogenic activities. However, the high degree of behavioral plasticity of many species within these communities allow them to cope with altered environmental conditions to some extent. Here, we combine meteorological information, data from hydroacoustic surveys, and recordings of goliath grouper sound production to examine the response of coastal fish communities to heavy rainfall events in South Florida, USA, that resulted in the release of excess storm water into surrounding estuaries and coastal waters. We observed a nearly 12,000% increase in water column acoustic backscatter following a heavy rainfall event of September 16th, 2015. Interestingly, estimates of school backscatter, a proxy for biomass, increased by 172% with the onset of the perturbation. Schooling fish density also increased by 182%, as did acoustically derived estimates of mean schooling fish length (21%). Following the perturbed period, school backscatter decreased by 406%, along with schooling density (272%), and mean schooling fish length (35%). Hydrophone and hydroacoustic data also revealed that goliath grouper (Epinephelus itajara) spawning aggregations were persistent in the region throughout the duration of the study and continued to exhibit courtship behavior during the perturbed period. Our observations demonstrate the high level of resistance common in coastal species but raises new questions regarding the threshold at which fish communities and reproductive activities are disrupted. As coastal land use continues to increase, and the effects of global climate change become more pronounced, more Before-After Control Impact (BACI) studies will provide improved insight into the overall response of nearshore communities to future perturbations and the cumulative effect of repeated perturbations over extended periods.