Víctor M. Tuset

Comparative morphology of the sagittal otolith in three species of south Caspian gobies

Sagittal otolith shapes were investigated in order to identify three sympatric species of south Caspian gobies (Caspian goby Neogobius caspius, deepwater goby Ponticola bathybius and bighead goby Ponticola gorlap). The sagittal otoliths in P. bathybius have a rectangular shape and are thick, whereas in N. caspius they are relatively round and thin. In P. gorlap, otoliths have an elongated shape and are relatively thick. The noticeable difference among the otoliths of the three species is the presence of one anterior and one posterior projection in the otoliths of N. caspius and P. gorlap. Among shape indices, form factor (irregularity of surface area), circularity, aspect ratio and rectangularity are the foremost that indicate interspecific variability. The canonical discriminant analysis correctly classifies 94·7% of the original group cases. The overall analyses show the relevance of applying otolith shape for interspecific distinction of the three species of Caspian gobies.

Life history of Plesionika edwardsi (Crustacea, Decapoda, Pandalidae) around the Canary Islands, Eastern Central Atlantic

The life history of Plesionika edwardsi (Brandt, 1851) around the Canary Islands in the Eastern Central Atlantic was investigated, based on a total of 11 434 shrimps ranging in length between 8 and 40 mm carapace length (CL). The species carries out seasonal migrations; they concentrate in deep water during winter, move shallower in summer and return to deep water again in autumn. Ovigerous females occur throughout the year, but a spawning peak was determined between April and September. The size at maturity for females was approximately 26 mm CL. Shrimp size generally increased with increasing water depth. The growth parameters for males were L ∞ = 25.75 mm CL and K = 0.55 year−1, and L ∞ = 28.28 mm CL and K = 0.66·year−1 for females. The species displays the typical reproductive pattern of tropical pandalids and is dioecious.

Comparison of different otolith shape descriptors and morphometrics for the identification of closely related species of Lutjanus spp. from the Persian Gulf

Abstract The anatomical and morphometric (shape indices, contour descriptors and otolith weight) characterizations of sagittal otoliths were investigated in 11 species of Lutjanus spp. inhabiting the Persian Gulf. This is the first study that compares the efficiency of three different image analysis techniques for discriminating species based on the shape of the outer otolith contour, including elliptical Fourier descriptors (EFD), fast Fourier transform (FFT) and wavelet transform (WT). Sagittal otoliths of snappers are morphologically similar with some small specific variations. The use of otolith contour based on wavelets (WT) provided the best results in comparison with the two other methods based on Fourier descriptors, but only the combination of the all three methods (EFD, FFT and WT) was useful to obtain a robust classification of species. The species prediction improved when otolith weight was included. In relation to the shape indices, only the aspect ratio provided a clear grouping of species.

Ecomorphological analysis as a complementary tool to detect changes in fish communities following major perturbations in two South African estuarine systems

Ecomorphological changes as a result of natural perturbations in estuarine fish communities were investigated in two South African estuaries (Swartvlei and East Kleinemonde), both before and after the loss of aquatic macrophyte beds in these systems. The fish communities were analysed using an ecomorphological diversity index (EMI) and the results compared to a traditional index, the Shannon-Wiener diversity index. The EMI revealed that the major changes in fish community composition recorded in both estuaries were associated with quantitative variations at the species level. Both estuaries essentially lost their macrophyte beds and ended up with the same type of bottom habitat (bare sediment). In both cases the fish morphological variability decreased immediately after aquatic macrophyte loss and then increased to end above the initial value. The ecomorphological analysis appeared to be sensitive to major ecological disturbances that occurred during the study period and this was confirmed by the morphospace configuration. The results indicate that the ecomorphology of the fish community responds to habitat changes and that this change corresponds to alterations in the representation of the different feeding types. These findings therefore contribute to the measurement of morphological changes in estuarine fish assemblages as a result of habitat changes within the ecosystem and we propose that ecomorphological analyses add another dimension to the information provided by existing diversity indices in studying changing fish communities.

Application of otolith mass and shape for discriminating scabbardfishes Aphanopus spp. in the north-eastern Atlantic Ocean

The otolith was used to investigate the variability between Aphanopus carbo and Aphanopus intermedius inhabiting the north-eastern Atlantic Ocean. The results indicate a high degree of morphological affinity between species and areas; a noticeable metabolic change in the otolith shape was noted in the specimens of A. carbo, which may be related to migrations of individuals from shallow water (closer to the continental coast) to deeper water (archipelagos of Madeira and the Canary Islands). The results suggest a single population for both species in the north-eastern Atlantic Ocean, although not conclusively.

Data on the family Pandalidae around the Canary Islands, with first record of Plesionika antigai (Caridea)

Of the 20 pandalid shrimps species and subspecies reported for the Eastern Central Atlantic (26–36° N), 16 were found in one or more Macaronesian archipelagos (Azores, Madeira, Canary Islands and Cape Verde Islands) (14–40° N), and 11 of them were recorded to date in the Canary Island waters (27° 30′–29° 30′ N): Bitias stocki Fransen, 1990; Heterocarpus ensifer ensifer A. Milne-Edwards, 1881; Heterocarpus grimaldii A. Milne-Edwards & Bouvier, 1900; Heterocarpus laevigatus Bate, 1888; Plesionika edwardsii (Brandt, 1851); Plesionika ensis (A. Milne-Edwards, 1881); Plesionika holthuisi Crosnier & Forest, 1968; Plesionika martia martia (A. Milne-Edwards, 1883); Plesionika narval (J.C. Fabricius, 1787); Plesionika williamsi Forest, 1964; and Stylopandalus richardi Coutière, 1905. In the present work, Plesionika antigai Zariquiey Álvarez, 1955 is recorded for the first time from the Canary Islands. As a result of many fishing surveys around the Canary Islands at 27–1550 m depth between 1985 and 1998, information on bathymetric distribution, habitat, size and biology of the 12 Canarian pandalid species is given. The geomorphologic, geographic and oceanographic characteristics of the Canary Islands marine ecosystems could explain the great diversity in the biogeographic patterns of the pandalid species inhabiting this area. The distribution patterns found were: Macaronesian (1 spec.), Atlanto-Mediterranean (1 spec.), Eastern Atlantic warm-temperate (1 spec.), amphi-Atlantic warm (2 spec.), amphi-Atlantic warm-temperate (1 spec.), pantropical (5 spec.), and cosmopolitan (1 spec.).

Otolith Patterns of Rockfishes from the Northeastern Pacific

Sagitta otolith shape was analysed in twenty sympatric rockfishes off the southern California coast (Northeastern Pacific). The variation in shape was quantified using canonical variate analysis based on fifth wavelet function decomposition of otolith contour. We selected wavelets because this representation allow the identifications of zones or single morphological points along the contour. The entire otoliths along with four subsections (anterior, ventral, posterodorsal, and anterodorsal) with morphological meaning were examined. Multivariate analyses (MANOVA) showed significant differences in the contours of whole otolith morphology and corresponding subsection among rockfishes. Four patterns were found: fusiform, oblong, and two types of elliptic. A redundancy analysis indicated that anterior and anterodorsal subsections contribute most to define the entire otolith shape. Complementarily, the eco‐morphological study indicated that the depth distribution and strategies for capture prey were correlated to otolith shape, especially with the anterodorsal zone. J. Morphol. 276:458–469, 2015.

Phenotypic plasticity in wild marine fishes associated with fish-cage aquaculture

Two opportunistic fish species associated with fish farms, bogue (Boops boops) and salema (Sarpa salpa), were studied to infer whether changes in their feeding habits may cause a phenotypic response in body and otolith shape. Specimens were collected close to aquaculture cage sites, called ‘wild-farmed fish’, and from control sites far away from these areas, called ‘wild fish’. The fish body shapes were examined with geometric morphometric analysis using 21 landmarks. The otolith contours were analysed using wavelet function, whereas otolith weights were used as indicators of fish growth rates. Statistically significant differences were observed in body shape between wild-farmed fish and wild fish of both species. The wild-farmed fish had a smaller head and eye, and in bogue also a slighter snout curvature and head depth. Otolith shape and weight did not differ between groups in bogue. By contrast, there were significant differences in otolith shape and weight between groups in salema. A complementary study in salema indicated that the wild-farmed fishes grew more in weight and accumulated higher concentrations of ‘terrestrial fatty acids’ (linoleic and alpha-linolenic acids), which are used in fish feeds. Our findings clearly demonstrated an influence of coastal sea cages on metabolism of some wild fishes.

Fishing methods for sustainable shrimp fisheries in the Canary Islands (North-West Africa)

During the past 20 years, experimental cruises have been conducted around the Canary Islands (North-West Africa) to investigate the biodiversity of the deep-sea ecosystem and to explore new fisheries resources. Although pandalid shrimps were shown to be very abundant in this region, information is lacking regarding the best fishing method for catching the different species of shrimp. Here, two types of traps were tested, a semi-floating shrimp trap and a traditional bottom trap, in an effort to improve the fishing gear effectiveness and to reduce the capture of non-target species. In total, nine species were captured, which were categorised into three main groups based on their depth of capture: Plesionika edwardsii, P. narval and P. holtuisi (100–400 m); P. ensis, P. martia, P. williamsi and Heterocarpus ensifer (400–800 m); and H. grimaldii and H. laevigatus (800–1 300 m). Significant differences were found in the capture of the different species: P. narval, P. ensis, P. edwardsii and H. ensifer were captured more readily using the semi-floating traps, whereas P. martia, P. williamsi, H. grimaldii and H. laevigatus were caught more efficiently with traditional bottom traps. This intra-specific difference in their capture was considered to be due to the differential motility of the species in the water column. There were indications that P. edwardsii and H. ensifer are an unexploited resource that has the potential to support a viable and sustainable fishery using semi-floating shrimp traps. Furthermore, the deeper-dwelling pandalid shrimps, H. laevigatus and H. grimaldi, could be a secondary target species using bottom traps.

Reproduction, Fecundity, and Growth of Abalone (Haliotis Tuberculata Coccinea, Reeve 1846) in the Canary Islands

ABSTRACT The abalone, Haliotis tuberculata coccinea has been considered in the Canary Islands as a potential candidate species for aquaculture to restock its natural ecosystem. Because the study and development of artificial culture techniques require as much information as possible on natural populations, 20 monthly H. tuberculata coccinea samples were collected in the island of Gran Canaria between June 2005 and May 2007. Reproductive biology was assessed by histological techniques, and von Bertalanffy growth parameters were also estimated. Ovarian morphology of H. tuberculata coccinea showed 6 sexual cell stages during the oogenetic process and a group synchronous ovarian development. Its reproductive cycle is characterized by an annual spawning period throughout the entire year, although the maximum reproductive activity of this population was observed between August and February. Batch fecundity ranged from 85,749 (shell length (SL), 39 mm)-691,456 (SL, 62 mm), and a significantly higher fecundity rate was observed in individuals with an SL larger than 55 mm, suggesting that, to optimize egg production, this is the minimum broodstock size to be used in hatcheries. With regard to the population structure, the overall maleto-female ratio was 1:1.02 and the data of the size class analysis did not show any tendency. The von Bertalanffy growth parameters estimated for females and males were 72.5 and 78.8 mm in SL of asymptotic length, and 0.43 year-1 and 0.37 year-1 of growth rate.