Figure - available from: Journal of Fish Biology
This content is subject to copyright. Terms and conditions apply.
Description of changes in Pacific halibut mean oocyte diameters with (a) developmental stage and (b) oocyte size distribution with individual fish developmental stage. Vertical broken lines separate the growth stages at the midpoint between mean oocyte developmental stage diameters. In (a), mean oocyte diameters are indicated by black circles, one‐ and two standard deviations are indicated by wide black and grey bars, respectively; and minimum and maximum values are indicated by narrow grey bars, with different letters (a–f) indicating statistical significance (P < 0.025) among groups. In (b) the distribution of oocyte diameters is represented as the proportional occupancy of ln(oocyte area) for each of the observed female developmental stages (defined as the most advanced stage of oocyte present in the sample population; PGpn, PGca, etc.), with n indicating the total number of oocytes measured from a sub‐set of females (number of individual fish shown in parentheses)
Source publication
Accurate characterization of oocyte development is essential to understanding foundational aspects of reproductive biology and successful management of Pacific halibut (Hippoglossus stenolepis). Here this study provides complete histological descriptions for eight oocyte developmental stages in addition to postovulatory follicles and demonstrates t...
Citations
... Teleost fish have different reproductive tactics, for example, migration [1][2][3], different types of spawning [4][5][6], parental care that occurs in different ways such as the storage of fertilized eggs in the mouth [7][8][9], the construction of nests and the maintenance of continuous aeration of the eggs [10][11][12]. In females, mature oocytes indicate some reproductive tactics such as the reproductive period [13,14] and type of spawning [15,16], and the animal's fecundity can be estimated [5,17,18]. ...
In this study, we evaluated the morphology and morphometry of the layers that make up the follicular complex surrounding mature oocytes in the six fish species Auchenipterichthys longimanus, Ageneiosus ucayalensis, Hypophthalmus marginatus, Baryancistrus xanthellus, Panaqolus tankei and Peckoltia oligospila, belonging to the order Siluriformes, which inhabit the Amazon basin. On the basis of the morphology and thickness of the layers of the follicular complex, the species were divided into two groups: 1- A. longimanus, A. Ucayalensis and H. marginatus and 2 – B. xanthellus, P. tankei and P. oligospila. The total thickness of the layers that make up the follicular complex showed a difference between type III and IV oocytes for all species of each group. Differences in the theca layer, follicular cells and zona radiata between species and between groups were submitted to statistical analysis. Morphologically, group 1 showed columnar follicular cells and thin zona radiata. Meanwhile, group 2 displayed a layer of cuboidal-shaped follicular cells layer and thicker zona radiata. These differences may be related to the environment and reproductive behaviors, as group 1 migrates without parental care and has eggs that are generally smaller and abundant. While group 2, represented by loricariidae, inhabit lotic environments, have reproductive tactics of parental care and eggs that are generally large and in small numbers. Therefore, we can infer that the follicular complex in mature oocytes can predict the reproductive tactics of the species.
... On the other American coast, Pacific halibut have been collected on their spawning grounds, with multiple lines of evidence of winter spawning seasonality (January-February). Evidence of spawning includes the appearance of POFs, and a more complete characterization of oogenesis and gonad maturation (e.g., maximum oocyte size = 2.0 -2.5 mm, a maximum reported GSI of 15% for females; Fish et al., 2020Fish et al., , 2022. ...
The data-limited nature of Atlantic halibut (Hippoglossus hippoglossus) in U.S. waters hampers evaluation of what may be a slow but steady rebuilding pattern. Here, we collaborate with the commercial fishery to design and implement a multi-gear sampling program that collected 100s of biological samples from throughout the Gulf of Maine in a five-year period, 2014-2018. Examination of sectioned otoliths revealed a maximum age of 12 years (females) and 13 years (males); in comparison, Atlantic halibut as old as 40-50 years have been collected elsewhere in the western North Atlantic. Growth modeling confirmed sexual dimorphism, with a larger asymptotic length (L ∞) for females (214 cm fork length [FL]) than males (195 cm FL). Estimates of median female length at maturity, L 50 , of 128 cm FL (124-132 cm, 95% confidence limits), and median female age at maturity, A 50 , of 9.6 years old (9.0-10.8 years), were longer and older than previous reports for the Gulf of Maine, likely resulting from our use of histological instead of macroscopic methods to classify maturity. Histology demonstrated that vitellogenesis initiated in individuals in spring, nearly a year prior to spawning, which allowed us to identify first-time (primiparous) spawners and provided the first potential evidence of skip spawning for this species. Finally, an index was developed to track the proportion of potentially mature females in the fishery, which showed an increasing trend; this qualitative tool may prove useful in a data-limited environment for evaluating the relative stock status of Atlantic halibut.
... Ovarian and testicular samples were collected from the same fish, preserved in RNAlater (Invitrogen) and stored at −80°C until processed for RNA extraction. Ovarian and testicular samples were also collected, fixed in 10% buffered formalin and processed for histological analyses to determine the reproductive stage, as described previously (Fish et al., 2020). Collected females and males for Pool-sequencing were at the early vitellogenic and early spermatogenic stages, respectively (data not shown). ...
The Pacific halibut (Hippoglossus stenolepis) is a key species in the North Pacific Ocean and Bering Sea ecosystems, where it also supports important fisheries. However, the lack of genomic resources limits our understanding of evolutionary, environmental and anthropogenic forces affecting key life history characteristics of Pacific halibut and prevents the application of genomic tools in fisheries management and conservation efforts. In the present study, we report on the first generation of a high‐quality chromosome‐level assembly of the Pacific halibut genome, with an estimated size of 602 Mb, 24 chromosome‐length scaffolds that contain 99.8% of the assembly and a N50 scaffold length of 27.3 Mb. In the first application of this important resource, we conducted genome‐wide analyses of sex‐specific genetic variation by pool sequencing and characterized a potential sex‐determining region in chromosome 9 with a high density of female‐specific SNPs. Within this region, we identified the bmpr1ba gene as a potential candidate for master sex‐determining (MSD) gene. bmpr1ba is a member of the TGF‐β family that in teleosts has provided the largest number of MSD genes, including a paralog of this gene in Atlantic herring. The genome assembly constitutes an essential resource for future studies on Pacific halibut population structure and dynamics, evolutionary history and responses to environmental and anthropogenic influences. Furthermore, the genomic location of the sex‐determining region in Pacific halibut has been identified and a putative candidate MSD gene has been proposed, providing further support for the rapid evolution of sex‐determining mechanisms in teleost fish.
... In the Gulf of Alaska, spawning occurs from November to March, peaks in late January (St-Pierre, 1984), and is likely accompanied by a spawning-rise behavior in which females ascend in the water column and eggs are released for fertilization at the peak of the rise (Loher and Seitz, 2008). In a recent study, we histologically described oocyte developmental stages in Pacific halibut that were used to assign female developmental stages, from early primary growth until the periovulatory stage (Fish et al., 2020). Importantly, we also provided evidence for a group synchronous ovarian developmental pattern with determinate fecundity in Pacific halibut (Fish et al., 2020). ...
... In a recent study, we histologically described oocyte developmental stages in Pacific halibut that were used to assign female developmental stages, from early primary growth until the periovulatory stage (Fish et al., 2020). Importantly, we also provided evidence for a group synchronous ovarian developmental pattern with determinate fecundity in Pacific halibut (Fish et al., 2020). However, no work has yet been conducted to characterize the temporal progression of reproductive development in female Pacific halibut that would allow for a better understanding of the reproductive cycle of the species and, importantly, the identification of physiological traits and biological indicators (e.g. ...
... Ovarian tissue samples were processed for histology as described in Fish et al. (2020). Slides were examined visually with a compound microscope (1x -100x magnification), and oocyte developmental stages were identified according to Brown-Peterson et al. (2011) and Grier et al. (2009) and used to assign the female developmental stage as described in Fish et al. (2020). ...
Developing a robust understanding of Pacific halibut reproductive biology is essential to understanding the different components (e.g. maturity) that determine the reproductive output of the species and, therefore, for estimating the relative female spawning biomass. With these, effective and proactive management strategies can be designed and implemented to face the large-scale environmental changes to which high-latitude spawning fish are particularly vulnerable. To date, reproductive studies of Pacific halibut have mainly focused on population or regional scales, leaving the specific details of organism-level reproductive development unexamined. The work described here aimed to address information gaps in Pacific halibut reproductive biology by conducting a detailed histological examination of temporal changes in ovarian development over an annual reproductive cycle with special attention to the use of biological indicators (e.g. oocyte diameter, gonadosomatic index, hepatosomatic index, Fulton’s condition factor, somatic fat) in characterizing female developmental stages and reproductive phases. Our results provide a foundation for future studies directed at improving current maturity estimations by histological assessment and explore models that test the utility of biological indicators to predict maturity in this important fish species.
... The information generated underlines the importance of using histology to understand both the reproductive cell biology and the reproductive strategy a species employs for maximum survival of the offspring. It also highlights the importance of histological analysis of oocyte developmental stages as an important step to evaluating current macroscopic maturity assessment methods (West, 1990;Fish et al., 2020). ...
