Margarida Casadevall

Feeding strategies of deep-water morids on the western Mediterranean slope

Abstract This study examines the feeding habits of Lepidion lepidion , the dominant species of fish and the most abundant morid inhabiting the deep slope of the Catalan Sea, and presents some data on the diet of the other two deep-water morids inhabiting this zone. Samples were obtained at depths between 1000 and 2200 m. The diet of L. lepidion was analysed in two size-classes and for three bathymetric strata. The feeding habits of L. lepidion included a broad range of benthic and pelagic prey. The planktonic prey are most abundant at 1000–1400 m and are almost entirelt absent at 1800–2200 m. Suprabenthos increases with depth. This difference may be the consequence of a change in available resources. There are ontogenetic differences in the diet of L. lepidion that are basically determined by the depth (below 1600 m only adult specimens are found). Lepidion guentheri and Mora moro were active predators of suprabenthic and epibenthic fauna. The bathymetric distribution of morids is also discussed in relation to a possible competitive interaction for similar resources.

Annual reproductive cycle of Helicolenus dactylopterus dactylopterus (Teleostei: Scorpaeniformes) with special reference to the ovaries sperm storage

In this paper the macroscopic and microscopic morphology of the gonads of Helicolenus dactylopterus dactylopterus (Pisces: Teleostei) were analysed as well as its seasonal histological changes. The testicles are of the lobular type. The cystovarian ovaries have a central rachis from which the ovigerous lamellae are radially suspended. The gonoducts remain independent until they join together at the urogenital papilla which, in males, can be projected towards the exterior serving as a copulating organ. Sperm production is important from July to February. In contrast, the females only have mature and vitellogenic oocytes in winter, from December to February. In the west Mediterranean spawning takes place during the months of January and February. The ovaries contain clusters of spermatozoa for some ten months, from May onwards. By means of an optical microscope a specialized structure is detected, situated at the base of the interlamellar space, where male sexual cells are stored for a long period of time. Nevertheless, for several months many individual spermatozoa are also detected in the interlamellar areas, floating in the ovarian fluid secreted by the epithelium of the ovarian wall. It is still unknown whether the species under study is oviparous or viviparous, as until now, no intraovarian embryos have been detected in any of the specimens analysed.

Agonistic sounds in the skunk clownfish Amphiprion akallopisos: size‐related variation in acoustic features

Fourteen individuals of the skunk clownfish Amphiprion akallopisos of different sizes and of different sexual status (non-breeder, male or female) were analysed for four acoustic features. Dominant frequency and pulse duration were highly correlated with standard length (r = 0.97), and were not related to sex. Both the dominant frequency and pulse duration were signals conveying information related to the size of the emitter, which implies that these sound characteristics could be useful in assessing size of conspecifics.

Sexual dimorphism of sonic apparatus and extreme intersexual variation of sounds in Ophidion rochei (Ophidiidae): first evidence of a tight relationship between morphology and sound characteristics in Ophidiidae

BackgroundMany Ophidiidae are active in dark environments and display complex sonic apparatus morphologies. However, sound recordings are scarce and little is known about acoustic communication in this family. This paper focuses on Ophidion rochei which is known to display an important sexual dimorphism in swimbladder and anterior skeleton. The aims of this study were to compare the sound producing morphology, and the resulting sounds in juveniles, females and males of O. rochei.ResultsMales, females, and juveniles possessed different morphotypes. Females and juveniles contrasted with males because they possessed dramatic differences in morphology of their sonic muscles, swimbladder, supraoccipital crest, and first vertebrae and associated ribs. Further, they lacked the ‘rocker bone’ typically found in males. Sounds from each morphotype were highly divergent. Males generally produced non harmonic, multiple-pulsed sounds that lasted for several seconds (3.5 ± 1.3 s) with a pulse period of ca. 100 ms. Juvenile and female sounds were recorded for the first time in ophidiids. Female sounds were harmonic, had shorter pulse period (±3.7 ms), and never exceeded a few dozen milliseconds (18 ± 11 ms). Moreover, unlike male sounds, female sounds did not have alternating long and short pulse periods. Juvenile sounds were weaker but appear to be similar to female sounds.ConclusionsAlthough it is not possible to distinguish externally male from female in O. rochei, they show a sonic apparatus and sounds that are dramatically different. This difference is likely due to their nocturnal habits that may have favored the evolution of internal secondary sexual characters that help to distinguish males from females and that could facilitate mate choice by females. Moreover, the comparison of different morphotypes in this study shows that these morphological differences result from a peramorphosis that takes place during the development of the gonads.

Fish remains from Arbreda Cave (Serinya `, Girona), northeast Spain, and their palaeoecological significance

This paper presents the study and palaeoecological analysis of fossil fish vertebrae of the Arbreda Cave (Serinya `, Girona), probably the most significant Catalan palaeolithic site. Morphological and radiographical studies were used to identify vertebrae to genus and, whenever possible, to species level. The taxa identified are: Anguilla anguilla, Barbus sp., Leuciscus sp., Rutilus sp., Salmo salar, Salmo trutta and Salmo sp. Species distribution at various archaeological levels provided palaeoecological data. There is a high proportion of Salmo trutta remains in the Upper Gravettian level and a sudden decrease of fossil fish bones in the Solutrean level with shouldered points. This decrease coincides with the period of lower temperatures of the Late Pleniglacial. Finally, the post-glacial terra rossa level is characterised by the absence of Salmo trutta remains. The presence of Salmo salar in Mediterranean sites has often been discussed. However, the dating of remains of this Atlantic species found in the Arbreda Cave makes it likely that these specimens were caught in Atlantic rivers on the northern Pyrennean slope and then transported to the area studied.

The Food of Seriola Dumerili (Pisces: Carangidae) in the Catalan Sea (Western Mediterranean)

Stomachs of 385 specimens of Seriola dumerili (Risso, 1810) have been analysed. Their coefficient of repletion is 50·8% in juveniles and 90·3% in adults. Juveniles feed almost exclusively on Teleostei with Engraulis encrasicholus and Sardina pilchardus as the main food; Cephalopoda ( Loligo vulgaris and Sepiola sp.) and Crustacea (Squilla mantis) are also eaten. Adults feed on a great diversity of Teleostei headed by S. pilchardus and Merluccius merluccius. According to Smith-Vaniz (1986) Seriola dumerili is both epibenthic and pelagic, occurring at 18–72 m in small to moderate schools. Juveniles are associated with flotsam in oceanic or offshore neritic waters. Adults often live near reefs or at deep off-shore holes or drop-offs. It is found from the Mediterranean and the Bay of Biscay to South Africa, from Nova Scotia to Brazil, and also in the Arabian Gulf, Australia, Japan and the Hawaiian Islands.

Fish Health and Fisheries, Implications for Stock Assessment and Management: The Mediterranean Example

Although fish health may influence key population-level processes, particularly those dealing with natural mortality, reproduction, and growth, which, in turn, affect stock productivity, little emphasis has been placed on the links between fish health and the management of marine fisheries. This article addresses this gap and illustrates how knowledge of fish health could provide insight for marine fisheries biologists, stock assessment modelers, and managers. The study proposes ways in which the consideration of condition indicators (energy reserves) and parasitism improves stock assessment and fisheries management, especially in situations of data shortage when standard methods cannot be applied, as is the case in many Mediterranean fish stocks. This article focuses on seven case studies of different fish species from the Mediterranean and Black Seas. Overall, and although the relationship between fish health and productivity cannot always be found or quantified, the article emphasizes the importance of the physical health of exploited stocks, particularly during critical life periods of the fish (e.g., prior to spawning, migration, or in the early life stages), as an essential element of sustainable and profitable fisheries. On the basis of these results, stock assessment and fisheries management implications are discussed.

Female reproductive biology of the bluemouth Helicolenus dactylopterus dactylopterus: spawning and fecundity

The bluemouth Helicolenus dactylopterus dactylopterus is a zygoparous species that spawns multiple batches of embryos enclosed within a gelatinous matrix. Oocyte development is asynchronous, and the recruitment of secondary growth oocytes occurs continuously during the developing phase, but stops before the start of the first spawning (i.e. fecundity is determinate). The number of developing oocytes can be estimated as a function of the total length of the fish, its ovary mass and its gonado-somatic index. Only at the onset of spawning, when potential fecundity is determined, does condition also have a significant effect. The low levels of atresia detected during most of the spawning season show that this mechanism does not substantially affect the process. There is variability both in the spawning interval (with a mean of 2 days) and in the number of embryos comprising every single batch (up to 37,000). Expected effect of fisheries on the reproductive traits of this deep-sea species is also discussed.

Reproductive indices and fecundity of Helicolenus dactylopterus dactylopterus (Teleostei: Scorpaenidae) in the Catalan Sea (western Mediterranean)

Various indices related to reproduction and the fecundity of Helicolenus dactylopterus dactylopterus (Teleostei: Scorpaenidae) were analysed. Sexual dimorphism does not occur in the population we studied and the sex ratio is always equal. The size of the species at sexual maturity is a standard length of 130 mm for males and 145 mm for females. The maximum gonadosomatic index values for males and females are temporally out of phase to a large degree, which explains the intra-ovarian storage of spermatozoa that occurs in this species. There are large hepatic reserves which are basically used in the synthesis of vitellogenin, while the mesentery fat reserves are not mobilized until the end of the maturation process of the oocytes. Multiple spawning takes place between January and February, consisting of between 11,000 and 87,000 eggs, of about 500 μm in diameter. The fecundity of the species is, with a high degree of correlation, determined by the size and weight of the individuals.

Sperm storage structures in the ovary of Helicolenus dactylopterus dactylopterus (Teleostei : Scorpaenidae): An ultrastructural study

The ultrastructure of ovarian sperm storage of Helicolenus dactylopterus dactylopterus is described, before and after the spawning period. The spermatozoa remain inside cryptal structures that are situated in the interlamellar gaps and are connected to the ovarian lumen by a duct. This complex forms a highly specialised structure. During the long storage period, crypts are richly vascularised. Their surrounding simple epithelia have intercellular junctions that may serve to protect the spermatozoa from the female immune system. At the moment during which insemination of mature oocytes occurs, the sperm may be expelled from cryptal structures by means of a spasmodic contraction. During the post spawning period, residual spermatozoa that remain in the crypts are eliminated by cryptal phagocytes. At the end of the process the crypts contain only an amorphous material.