Deepwater Redfish Research Articles

Drivers of growth in strong year classes of the deepwater redfish (Sebastes mentella) population from the Gulf of St. Lawrence derived from otolith increment-based growth chronologies.

The case of the deepwater redfish (Sebastes mentella) in the Gulf of St. Lawrence (GSL) is a compelling example of drastic fluctuations in annual recruitment strength, characteristic of spasmodic stocks. After three decades of low abundance, the emergence of three consecutive strong year classes in 2011-2013 resulted in an unprecedented increase in biomass. In spasmodic stocks such as GSL redfish, strong year classes sustain both the biomass and catch for decades. Therefore, understanding the growth dynamics of these cohorts is essential. In the present study, we reconstructed the annual growth rates of redfish using otolith increment-based annual chronology and investigated the drivers of growth variation in redfish strong year classes of the early 2010s and early 1980s. Stock biomass was identified as the main extrinsic driver of redfish growth, suggesting intense competition for food at high conspecific density. Warming of deep waters in the GSL, where adult redfish settle, positively correlated with individual growth. However, recent warming of the cold intermediate layer showed a negative correlation with redfish growth, likely related to the shrinking of the habitat this water mass provides for various redfish cold-water prey rather than to a direct effect of temperature. Reconstruction of redfish annual growth trajectories from birth to capture emphasized the importance of carryover effects in the growth potential of strong year classes. This work provided an important first outlook of the factors driving growth variation in GSL redfish spasmodic stock and explored midterm consequences of density-dependent pressures on biological parameters of the population.

Reduction in size-at-maturity in unprecedentedly strong cohorts of redfish (Sebastes mentella and S. fasciatus) in the Gulf of St. Lawrence and Laurentian Channel.

Life-history traits, such as size-at-maturity, are key parameters to model population dynamics used to inform fisheries management. Fishery-induced evolution, density-dependent effects, and global warming have been shown to affect size- and age-at-maturity, and resulting spawning stock biomass (SSB) in a wide range of commercial fish stocks. Marked changes in redfish biomass and environmental conditions in the Gulf of St. Lawrence and Laurentian Channel over the past decade called for a review and update of size-at-maturity for commercially important deepwater redfish Sebastes mentella and Acadian redfish Sebastes fasciatus stocks. Following a 25-year moratorium, local redfish biomass has recently reached unprecedented levels, co-occurring with an overall warming of bottom water temperatures. Our objectives were (1) to perform a histological assessment of redfish reproduction stages, including the validation and fine-tuning of a robust visual chart to facilitate monitoring of size-at-maturity and SSB in a transforming environment, and (2) to evaluate changes in size-at-maturity in unprecedentedly strong cohorts of redfish, and consequences for stock status assessment and fisheries management. Each specimen was genetically identified to species, and gonad reproduction stages were determined by histology and macroscopic appearances. The present study enabled a robust visual chart for continued and cost-effective monitoring of redfish reproduction stages to be refined and validated, and has shown a large decrease in redfish length when 50% of the individuals are considered mature that led to an increase in estimates of SSB during the 2011-2021 period for S. mentella and S. fasciatus. These changes modified the perception of stock status, thus having significant implications for fisheries management. Given that fishery-induced evolution and community structure changes along with global warming are affecting numerous stocks worldwide, the present study outlines a major and global challenge for scientists and resources managers. As shown by our results, the monitoring and frequent updates of life-history traits in transforming environments are needed to provide reliable science advice for sustainable fisheries.

Organic UV absorbents in the deepwater redfish (Sebastes mentella) from the St. Lawrence Estuary and Gulf: Distribution and human health risk assessment

UV absorbents (UVAs), such as organic UV filters (UVFs) and benzotriazole UV stabilizers (BZT-UVs), are used in a wide range of consumer and industrial products and they are contaminants of emerging concern in the environment. However, their occurrence and fate in the deep-sea environments are inadequately understood. This study investigated the occurrence and distribution of five UVFs and ten BZT-UVs in the muscle (n = 127) of 2019-collected deepwater redfish (Sebastes mentella) from the St. Lawrence Estuary and Gulf (SLEG) (Canada) to better understand the accumulation of these contaminants in deep-sea fish. Small redfish (<30 cm) tended to have higher concentrations of UVAs in the muscle than that of larger specimens (>30 cm). The UVF 2-hydroxy-4-methoxybenzophenone (BP3) was the most frequently detected (present in 34 % of all samples) target UVA, with concentrations as high as 413 ng/g (dry weight). According to the δ15N and δ13C data, pelagic-eating redfish, and individuals with lower trophic levels had higher lipid content and accumulated more BP3 in their muscles. Four BZT-UVs were detected in redfish muscle, but the detection frequency was lower than 30 %. The estimated hazard quotient for these contaminants was <2.3 × 10−2 for general Canadian populations, indicating that they are unlikely to pose health risks to humans through redfish consumption. Factors influencing UVAs bioaccumulation in redfish, as well as the effects UVAs may have on deep-sea species, should be researched further.

Spatial distribution and speciation of mercury in a recovering deepwater redfish (Sebastes mentella) population from St. Lawrence Estuary and Gulf, Canada

Mercury (Hg) pollution poses a significant threat to the environment, particularly in the form of methylmercury (MeHg). However, little is known about the distribution and influencing factors of Hg in deep-sea (>200m) fish, which is crucial for assessing potential health risks to fish and humans. In Canada, the deepwater redfish (Sebastes mentella) has been designated as an endangered species. After a 25-year fishing moratorium, the redfish population in the St. Lawrence Estuary and Gulf is recovering, and resuming of commercial fishing and human consumption are expected. This study aimed to investigate the distribution of MeHg and total Hg (THg) in the muscle of redfish, as well as the factors influencing its distribution, and to assess the potential human health risks associated with redfish consumption. The redfish samples (n = 123) were collected by Fisheries and Oceans Canada in 2019. The concentrations of THg and MeHg in redfish muscle were determined to be 93.3 ± 183 ng/g (mean ± SD, wet weight) and 78.2 ± 149 ng/g, respectively. Large redfish (>30 cm) accumulated 20 to 30 times more Hg than small redfish (17–30 cm). Small redfish from the Estuary-Western Gulf had higher levels of MeHg and THg than those from the Laurentian Channel and the Northeast Gulf, but the Hg availability to redfish among the three areas were similar. Significant predictors of MeHg concentrations in redfish muscle were determined to be fish length, muscle moisture, δ15N, and N%. MeHg consumption by the general population with an average fish consumption rate is not anticipated to have adverse effects. This study establishes a baseline for future Hg monitoring in the deep water environments in this region. Further research is required to elucidate the cause-effect relationships between various environmental/biological parameters and Hg accumulation in deep-sea biota.

Spatiotemporal variability in otolith elemental fingerprint and the potential to determine deepwater redfish (Sebastes mentella) origins and migrations in the Estuary and Gulf of St. Lawrence, Canada

Connectivity processes have major implications in defining the resiliency of fish populations to overexploitation. A preliminary estimate of population exchange rates can be done by identifying the natal origin of adult fish. In this study, otolith elemental fingerprints were used as natural marker of origins and movements of Deepwater redfish (Sebastes mentella) in the Gulf of St. Lawrence (GSL). We specifically targeted the strong 2011–2013 cohorts that supported the rapid recovery of the GSL stock after its collapse in the 1990s. Elemental fingerprints were extracted from the core (proxy for larval origin) and edge (proxy for capture location) of otoliths using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We observed an East to West gradient in the multi-elemental fingerprint of the otolith edge in the GSL, as well as evidence of temporal variation between 2016 and 2018. Cluster analysis of the core fingerprint revealed the existence of two chemically distinct natal sources of variable contribution between the Saguenay Fjord, the western GSL and the eastern GSL. This new insight on the population structure of redfish in the GSL at an ecologically relevant scale constitutes important knowledge for the assessment and sustainable management of a key recovering resource.

Using gene expression to identify the most suitable environmental conditions for growth and metabolism of juvenile deepwater redfish (Sebastes mentella) in the Estuary and the Gulf of St. Lawrence

Abstract Deepwater redfish Sebastes mentella will be among the most important resource-sustaining commercial bottom-fish fisheries in the years to come in the Estuary and Gulf of St. Lawrence (EGSL). In 2011, 2012, and 2013, three strong cohorts were recruited to the stock; their abundance in 2018 was 80 times higher than that of the 1993–2012 period. The main goal of this work was to deepen our knowledge of their growth regulation and metabolism in order to identify molecular indicators and determine how they are influenced by natural environmental conditions. Fish weight and water temperature explained 11% of the variation in relative mRNA levels of specific gene targets in liver and muscle among seven sites where deepwater redfish were captured in the EGSL. The relative expression of liver insulin-like growth factor-1 (igf-1) and white muscle A-chain lactate dehydrogenase (ldh-a) correlate positively with weight, whereas heavy chain muscle myosin (myo), heart citrate synthase (cs), and white muscle pyruvate kinase (pk) correlate negatively. The relative expression of heart cytochrome c oxidase subunit 1 (cox-1) and white muscle igf-1 receptor isoform a (igf-1ra) correlate negatively with temperature. Deepwater redfish from the estuary were smaller than those caught at other sites. Since the growth potential of deepwater redfish was strongly correlated with temperature (being enhanced by higher temperatures), this study suggests an ecological advantage for this species in a climate-warming context.

The first complete mitochondrial genome of Actinopyga from Actinopyga echinites (Aspidochirotida: Holothuriidae)

The deep-water redfish, Actinopyga echinites, is an ecologically and economically important holothuroid in China due to its valuable nutrition and pharmacological compounds. However, the taxonomy and phylogeny of the Actinopyga have been debated and misidentifications have been reported recently. Moreover, there remain considerable doubts about cryptic species complex within Actinopyga. In this study, we report the first complete mitochondrial genome of Actinopyga from A. echinites. The mitogenome has 15,619 base pairs (62.9% A + T content) and made up of a total of 37 genes (13 protein-coding, 22 transfer RNAs, and 2 ribosomal RNAs), and a putative control region. This study was the first available complete mitogenome of Actinopyga and will provide useful genetic information for future phylogenetic and taxonomic classification of Holothuriidae.

Eliminating implausible fisheries assessment models using fishers’ knowledge

Peer review of competing deepwater redfish (Sebastes mentella) assessment models revealed data inconsistencies where stock biomass decline shown by the survey in the 1990s was too rapid to be explained solely by reported catch. The models invoked different techniques to achieve fits, one by changing mortality at age and the other by survey weighting. The former fitted reported catch well, while the latter accepted a mismatch between reported and estimated catch. The assessments produced different estimates of historical stock size and future productivity. Interviews conducted with fishers of the stock suggested that catch was at least twice as high as the official record. In light of the fishers’ evidence, the model that invoked a large change in mortality with age to follow reported catch closely now appears less credible. This serves as a warning against introducing new biological mechanisms without credible justification. This is an example of how indicators derived from fisher’s knowledge, even if only from a small number of interviews, can be used to eliminate less plausible models.

The effects of ambient temperature and holding time during processing on drip of saithe (Pollachius virens) and deepwater redfish (Sebastes mentella) fillets

The aim of this study was to investigate the effects of ambient temperatures (9, 16, 21 °C) and holding time (0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 h) on rate and quantity of temperature changes and drip losses for whitefish fillets. Different types of fillets were used for the experiment, fresh deepwater redfish (Sebastes mentella) fillets (105 g) and two sizes of saithe (Pollachius virens) fillets (289 g and 634 g). The fillet temperature increased with time, and more rapidly at higher ambient temperatures, particularly with smaller sized fillets. Similarly, the rate and quantity of drip formation were affected by all experimental factors. The effects decreased (p < 0.05) in the following order: holding time > type of fillets > ambient temperature. The rate of changes in both temperature and drip loss were greater during the first hour of holding but levelled off with longer holding time. Results indicated that time-temperature abuse, even during relatively short (<1 h) exposure of fillets, may lead to significant economic losses due to weight reduction of the products.

Image-enhanced burnt otoliths, bomb radiocarbon and the growth dynamics of redfish (Sebastes mentella and S. fasciatus) off the eastern coast of Canada

Many past attempts to age deep-water redfish (Sebastes mentella) and Acadian redfish (S. fasciatus) in the north-west Atlantic have been stymied by inappropriate ageing methods, the absence of age validation and the failure to differentiate among species. Herein we report substantial improvements in methods for ageing Sebastes spp. by linking the established ‘crack and burn’ method to modern sectioning and image-enhancement protocols. Bomb radiocarbon assays of the otolith core and monitoring of year-class progression confirmed the accuracy of the resulting age determinations to an age of 46 years. The use of microsatellite DNA to confirm species identity eliminated past confusion caused by species mixtures. Age determinations of 1252 redfish from the eastern coast of Canada demonstrated the presence of significant differences in growth rate and longevity both between the two redfish species and among populations and stocks, with a maximum observed longevity of 70 years. Even within species and stocks, an individual fish with a fork length of 38cm could be anywhere between 15 and 50 years of age, highlighting a near cessation of somatic growth after sexual maturation. In keeping with other deep-water species, sustainable management will require more attention to the low productivity expected of redfish stocks, rather than the high initial biomass that can support short-term but high catch rates.

Structure and specific features of formation of aggregations of deepwater redfish Sebastes mentella (Scorpaenidae) in the Norwegian Sea pelagial

Results of studies of the structure and specific features of formation of aggregations of deepwater redfish Sebastes mentella in the Norwegian Sea pelagial are provided. Data on the biological characteristics of S. mentella from different regions of the Norwegian Sea pelagial do not allow us to consider its aggregations as separate populations. On the basis of comparative analysis of the structure of aggregations in the Norwegian Sea and of population parameters and specific features of the life cycle of S. mentella in different parts of the Atlantic Ocean, its complex intraspecies organization at sites of overlapping of two largest populations—North Atlantic and Norwegian-Barents Sea-was established. The formation of pelagic aggregations in the water area of the Norwegian Sea occurs due to migration of maturing and mature individuals from the adjoining water areas. In the southern areas of the Norwegian Sea, dominant recruitment comes from the pelagial of the northeastern part of the Irminger Sea, which is promoted by the direction of streams of the North-Atlantic Current; it is not excluded either that fish can migrate to the southern part of the sea from the slopes of the Faeroes, Faeroes-Icelandic threshold, and the western coast of Norway. Migration to the northern areas of the sea is mainly performed by rapidly maturing fish from the rearing region from the western slopes of the Barents Sea and Spitsbergen Archipelago. The presence of seasonal migrations hinders the formation in the pelagial of perch isolated groups and promotes their migration.

Biological and genetic characteristics of deepwater redfish Sebastes mentella (Scorpaenidae) from the open part of the Norwegian Sea

The analysis is conducted of the biological and genetic characteristics of deepwater redfish Sebastes mentella from the open part of the Norwegian Sea. A similarity of the studied sample with analogous groups of deepwater redfish from the Northeast Atlantic in biological parameters and their dynamics is revealed. Polymorphism is registered in three of the nine studied enzyme loci: malic enzyme (NADF-dependent malatedehydrogenase), MEP-1*; phosphoglucomutase from the liver, PGM-2*; and glucose-6-phosphateisomerase, PGI*. A pairwise comparison of allele frequencies shows a similarity of the samples of deepwater redfish from the enclave of the Norwegian Sea. In addition, based on a pairwise analysis, significant differences are absent between the samples with similar biological characteristics from the open part of the Norwegian Sea and the Irminger Sea.

The distribution and specific features of the biology of deepwater redfish Sebastes mentella (Scorpaenidae) during mating in the pelagial of the northern Atlantic

Data on the spatial-bathymetric distribution, size and age composition, sex ratio, and feeding of deepwater redfish Sebastes mentella in the pelagial of the northern Atlantic (Irminger and Labrador seas) during mating are provided. From 1982 to 1999, the mating of S. mentella took place in the central and southern parts of the Irminger Sea (56°–62° N, 30°–43° W); since 2000 it took place in two geographically isolated areas: in the water area of the open part of the Labrador Sea, at sites of the south of the Irminger Sea adjacent to it (54°–58° N, 38°–50° W), and above the western slopes of the Reykjanes Ridge (62°–65° N, 25°–34° W). It is assumed that during mating in the northern area mixed aggregations of two ecological groups of S. mentella—an oceanic group that distributes in the pelagial and a bottom group that inhabits the slopes of Iceland—are formed. The formation of isolated areas of mating of the species is determined by the orientation of feeding migrations that are simultaneously migrations to spawning grounds. Fish of medium sizes migrate to spawning grounds in the southwestern direction, while large fish migrate in the northern direction; the fertilization of females in these areas occurs at the end of summer. In S. mentella, the seasonal and age differences in food composition are clearly pronounced. With the onset of mating, the males’ intensity of feeding in both regions decreases by a factor of 1.5–2.0, while females continue to feed actively.

Trophic structure of the Barents Sea fish assemblage with special reference to the cod stock recoverability

The species composition and trophic structure of the Barents Sea fish assemblage is analysed based on data from research survey trawls and diet analyses of various species. Atlantic cod was the dominant fish species encountered, accounting for more than 55% by abundance or biomass. Only five fish species (long rough dab, thorny skate, Greenland halibut, deepwater redfish and saithe) were sufficiently abundant to be considered as possible food competitors with cod in the Barents Sea. However, possible trophic competition is not high, due to low spatial and temporal overlap between cod and these other species. Analyses of fish assemblages and trophic structures of the Barents Sea and other areas (North Sea, Western Greenland, Newfoundland-Labrador shelf) suggest that Barents Sea cod is the only cod stock for which the ability to recover may not be restricted by trophic relations among fishes, due to a lack of other abundant predatory species and low potential for competition caused by spatial-temporal changes.

Population Structure of Deep‐Sea and Oceanic Phenotypes of Deepwater Redfish in the Irminger Sea and Icelandic Continental Slope: Are They Cryptic Species?

AbstractThe deepwater redfish Sebastes mentella has a wide distribution in the North Atlantic Ocean. In the Irminger Sea, there is evidence for two phenotypes (deep‐sea and oceanic) of deepwater redfish. The two phenotypes have overlapping geographic distributions but differ in depth preferences. There are two hypotheses on deepwater redfish stock structure in the Irminger Sea. One suggests that mature individuals of a single stock segregate according to size and age and therefore that the phenotypes represent different life stages of the same stock. The other hypothesis suggests that there are two different stocks and that these stocks segregate mainly according to depth. Additionally, it is not clear whether the fish of the deep‐sea phenotype in the Irminger Sea and those on the Icelandic continental shelf represent one stock. Analysis of genetic variability at eight allozyme markers in 1,763 deepwater redfish from 26 samples collected at different depths in the Irminger Sea and the Icelandic continental slope showed a significant difference between deep‐sea and oceanic samples, suggesting the presence of two distinguishable stocks. This is supported by (1) significant heterozygote deficiency at most loci in pooled samples, (2) extensive allele frequency differences between samples classified as belonging to deep‐sea and oceanic phenotypes, and (3) clustering of deepwater redfish samples of the same phenotype in a neighbor‐joining dendrogram and in Bayesian analyses (STRUCTURE and the ΔK procedure for determining the number of clusters). The results indicate that deepwater redfish stock structure should be taken into account for sustainable fisheries management in the Irminger Sea and adjacent waters.

Biological and ecological characteristics of deepwater redfish Sebastes mentella (Scorpaenidae) at different depths in the pelagial of the Irminger Sea

Results of comparative analysis of several ecological and biological indices of Sebastes mentella from the northern Atlantic (the Irminger Sea, Reykjanes Ridge) inhabiting different depths, 0–500 and 501–1000 m, are provided. A considerable similarity in the rates of linear and weight growth, sexual maturation, composition of parasitofauna, the degree of invasion by parasites of most species, specific features of invasion by copepod Sphyrion lumpi, as well as the pattern of pigment formations on the skin of S. mentella from two studied layers, testify to the absence of isolated groups of this species in the pelagial of the Irminger Sea. It was established that the formation of perch aggregations at a depth larger than 500 m takes place due to a partial redistribution from the upper layer of individuals aged 5 to 18 years and a complete departure to large depths of perch individuals older than 18 years. A conclusion was made that it is incorrect to use as a criterion for the intraspecies differentiation of the perch the insignificant differences in the occurrence of pigment formations on the skin that are the result of age changes in fish and an obvious pathology of this phenomenon. A decrease in the occurrence of melanin inclusions in the muscular tissue of fish at a depth larger than 500 m is also related to age changes and the change in the diet of the perch. Vertical variation, in particular biological parameters in pelagic aggregations, was determined by specific features of biology, ecology, and the life cycle of the species. In establishing measures of control of the international fishery in the pelagial of the Irminger Sea, it is necessary to proceed from the unity of aggregations of S. mentella throughout the vertical of their distribution.

An analysis of by-catch in the Icelandic blue whiting fishery

Abstract By-catch arising in the period May–November 2003 in the Icelandic blue whiting fishery was analyzed by random collection of 450 catch samples selected from 42 trips (9.4% of the total). By-catch species in the samples were quantified and their length measured. In general, by-catch was a relatively rare occurrence, but associated with rather wide confidence limits. Saithe and silver smelt were recorded in 21.1% and 19.1% of samples, respectively. Their total by-catch was 1605 and 1188 t, respectively. Lumpfish, cod, golden redfish and deepwater redfish were recorded in 2.2–5.6% of samples, and their total by-catch was 30–156 t by species. The remaining five fish species were recorded in

Genetic structure of deep-water redfish, Sebastes mentella , populations across the North Atlantic

Patterns of genetic diversity of the marine deep-water redfish, Sebastes mentella Travin, from 21 sampling locations (n=46 per sample, from 1995 to 1998) were examined throughout its range in the North Atlantic. Eight microsatellite loci were used in order to: (1) define the genetic structure and consider the possible influence of dispersal, geographic distance, oceanic currents and historical factors; and (2) relate the structure to present management units and practices. Three divergent population units (mean θ=0.012) associated with distinct geographic areas were defined: Eastern (Norway and Barents Sea), Panoceanic and Western (Gulf of St. Lawrence and offshore Newfoundland). The most important observation was the lack of genetic differences (mean θ=–0.0004) and lack of genetic isolation by geographic distance (r=0.318, P=0.112) among samples within the Panoceanic zone, from the Faroe Islands to the Grand Banks (6,000 km). A combination of vicariance, historical introgression with a closely related species, S. fasciatus, and contemporary patterns of oceanic circulation are likely to have shaped the observed population structure. These results only partially support current management units, and call for more integrated practices for regulating the exploitation of S. mentella throughout its extensive range.

Biochemical separation of Atlantic Canadian redfish: Sebastes mentella and Sebastes norvegicus

One of the problems for management of the redfish fishery in the Gulf of St. Lawrence is the difficulty in distinguishing between the different species: deepwater redfish (Sebastes mentella), golden redfish (Sebastes norvegicus), and Acadian redfish (Sebastes fasciatus). Controversy exists concerning whether S. mentella and S. norvegicus are separate species because of similarity of meristic characters and other attributes. We describe a procedure that distinguishes these two forms by isoelectric focusing using polyacrylamide gels of water-soluble muscle proteins. In our samples, the lower part of the gel of S. mentella consistently shows three major protein bands, while that of S. norvegicus shows only one major band. The isoelectric focusing banding patterns from our study agree with those found by other workers for redfish from Greenland and Norway. The unequivocal isoelectric focusing separation and its concordance with morphometric characters indicate that S. mentella and S. norvegicus are genetically distinct, reproductively isolated species.

Chromatoblastomas and related pigmented lesions in deepwater redfish, Sebastes mentella (Travin), from North Atlantic areas, especially the Irminger Sea

Abstract This study involved 34 960 specimens of deepwater redfish, Sebastes mentella (Travin), from the North Atlantic, 21 460 of them from the Irminger Sea. One hundred and three specimens of this species, 96 with pigmented lesions, were examined histologically. The black patches on the redfish skin proved to be superficial melanosis (48 cases) and deep melanosis (24 cases). Skin pterinophorosis was noted in 20 cases. Pigment tissue neoplasms were observed in 26 fish; all were benign chromatoblastomas. Fourteen tumours were diagnosed as melanomas originating from melanophores, seven as pterinophoromas originating from pterinophores, and five as pterino‐melanophoromas or melano‐pterinophoromas of mixed origin of both chromatophore types. The tumours on the trunk of redfish occurred only in pigmented areas larger than 20 cm2. Fish with such areas constitute no more than 2.4% of the total Irminger Sea redfish population. Most (76.2%) of pigmented lesions in this redfish population did not exceed 5 cm2 in area. The arrangement of pigmented areas differed in males and females. In females, 97% of patches were found between the pectoral and the first dorsal fins, whilst in males, 84% of patches were situated on the head and caudal fin. Pigmented lesions occurred 2–5 times more often in females than males. The causes of pigment tissue neoplasms and pigmented lesions in deepwater redfish are unknown.