Biology of the red mullet mullus surmuletus (mullidae) off the Canary Islands, Central-East Atlantic

The biology of red mullet Mullus surmuletus was studied from collections taken off the Canary Islandsbetween January 1991 and September 1993. Total length ranged from 12 to 33 cm, mainly between 15 and 21cm. Males ranged from 14 to 26 cm and females from 14 to 33 cm. Females dominated the larger size-classes (>18 cm). The overall ratio of males to females was 1:2.3. The reproductive period extended from February toMay, spawning peaking in March and April. The total length at 50% maturity was 16.6 cm for the whole population.The length-mass relationship for all individuals can be described by the parameters a = 0.0074 and b = 3.1826. Fish aged 0.8 years were present in the samples. The parameters of the Von Bertalanffy growth equation obtained for all individuals were: L‡ = 35.71 cm and k = 0.22.year-1. Significant differences were found in the growth parameters between males and females. The rates of total mortality Z, natural mortality M and fishing mortality F were 1.25, 0.55 and 0.70.year-1 respectively. The estimated total length at first capture was 15.74 cm

Ecological and evolutionary consequences of alternative sex-change pathways in fish

Sequentially hermaphroditic fish change sex from male to female (protandry) or vice versa (protogyny), increasing their fitness by becoming highly fecund females or large dominant males, respectively. These life-history strategies present different social organizations and reproductive modes, from near-random mating in protandry, to aggregate- and harem-spawning in protogyny. Using a combination of theoretical and molecular approaches, we compared variance in reproductive success (V k*) and effective population sizes (N e) in several species of sex-changing fish. We observed that, regardless of the direction of sex change, individuals conform to the same overall strategy, producing more offspring and exhibiting greater V k* in the second sex. However, protogynous species show greater V k*, especially pronounced in haremic species, resulting in an overall reduction of N e compared to protandrous species. Collectively and independently, our results demonstrate that the direction of sex change is a pivotal variable in predicting demographic changes and resilience in sex-changing fish, many of which sustain highly valued and vulnerable fisheries worldwide

Bordetella pertussis Infection or Vaccination Substantially Protects Mice against B. bronchiseptica Infection

Although B. bronchiseptica efficiently infects a wide range of mammalian hosts and efficiently spreads among them, it is rarely observed in humans. In contrast to the many other hosts of B. bronchiseptica, humans are host to the apparently specialized pathogen B. pertussis, the great majority having immunity due to vaccination, infection or both. Here we explore whether immunity to B. pertussis protects against B. bronchiseptica infection. In a murine model, either infection or vaccination with B. pertussis induced antibodies that recognized antigens of B. bronchiseptica and protected the lower respiratory tract of mice against three phylogenetically disparate strains of B. bronchiseptica that efficiently infect naïve animals. Furthermore, vaccination with purified B. pertussis-derived pertactin, filamentous hemagglutinin or the human acellular vaccine, Adacel, conferred similar protection against B. bronchiseptica challenge. These data indicate that individual immunity to B. pertussis affects B. bronchiseptica infection, and suggest that the high levels of herd immunity against B. pertussis in humans could explain the lack of observed B. bronchiseptica transmission. This could also explain the apparent association of B. bronchiseptica infections with an immunocompromised state

Life-history traits of seabream Boops boops (Linnaeus, 1758) in the central eastern Atlantic Ocean (Canary Islands)

Life-history traits of the sparid Boops boops are studied for the first time in an isolated Atlantic population. Boops boops is a hermaphrodite species  characterised by late gonochorism or non-functional hermaphroditism. The 1:0.852 ratio of females to males was significantly different from unity. Both sexes had similar size distributions; however, females outnumbered males at sizes of between 16 and 18 cm TL, whereas males predominated among fish larger than 28 cm TL. The average lengths at first maturity for females and males were 16.02 (SD 0.28) and 16.49 (SD 0.25) cm TL, respectively, with no significant difference between sexes. Spawning-capable females were first observed in January, at a low percentage, and were present until May. The gonadosomatic index of both females and males peaked in February. Vitellogenesis did not begin synchronously, and the simultaneous presence of oocytes in all stages of development indicated an asynchronous mode of ovarian development. The presence of  postovulatory follicles, together with tertiary-yolk-vesicle oocytes, indicates that the species is a multiple spawner. An age–length key showed an age-group composition for females of between 0 and 4 years, whereas males were between 0 and 5 years. The von Bertalanffy growth parameters for  females were L∞ = 32.3 cm TL, k = 0.44 y–1 and t0 = −0.81 y, and for males they were L∞ = 35.3 cm TL, k = 0.38 y–1 and t0 = −0.80 y.Keywords: age, gonad histology, growth, maturity, otoliths, reproductive cycle, sex ratio, spawning perio

Validation of age determination methods and growth studies of the sand sole Pegusa lascaris (Soleidae) from the eastern-central Atlantic

The age and growth of the sand sole Pegusa lascaris from the Canarian Archipelago were studied from 2107 fish collected between January 2005 and December 2007. To find an appropriate method for age determination, sagittal otoliths were observed by surface-reading and frontal section and the results were compared. The two methods did not differ significantly in estimated age but the surface-reading method is superior in terms of cost and time efficiency. The sand sole has a moderate life span, with ages up to 10 years recorded. Individuals grow quickly in their first two years, attaining approximately 48% of their maximum standard length; after the second year, their growth rate drops rapidly as energy is diverted to reproduction. Males and females show dimorphism in growth, with females reaching a slightly greater length and age than males. Von Bertalanffy, seasonalized von Bertalanfy, Gompertz, and Schnute growth models were fitted to length-at-age data. Akaike weights for the seasonalized von Bertalanffy growth model indicated that the probability of choosing the correct model from the group of models used was >0.999 for males and females. The seasonalized von Bertalanffy growth parameters estimated were: L∞ = 309 mm standard length, k = 0.166 yr–1, t0 = –1.88 yr, C = 0.347, and ts = 0.578 for males; and L∞ = 318 mm standard length, k = 0.164 yr–1, t0 = –1.653 yr, C = 0.820, and ts = 0.691 for females. Fish standard length and otolith radius are closely correlated (R2 = 0.902). The relation between standard length and otolith radius is described by a power function (α = 85.11, v = 0.906).

Age and growth of the annular seabream, Diplodus annularis (Pisces: Sparidae), from the Canarian archipelago (central-east Atlantic)

Age and growth of the annular seabream Diplodus annularis off the Canary Islands (Central-east Atlantic) were studied. The length range of fish was between 82 and 209 mm in total length. Otoliths showed clear growth rings. Two rings, one opaque and one translucent, were laid down each year on the otoliths. Seasonal growth cycles were related to physiological changes produced by the influence of temperature and reproductive cycle.The opaque ring was deposited during the summer months and the translucent one during the winter months. Individuals aged 0 to 6 years were found. After the first year, the annual growth rate droped rapidly as a consequence of the sexual maturity. The difference in size between males and females was not considered as evidence of an intersexual difference in growth rates since they are the same specimens at different stages of sexual succession. The parameters of the von Bertalanffy growth equation for all individuals were: L∞ = 248.5 mm, k = 0.259 year–1, and t0 = –0.871 year. The backcalculation method demonstrated the validity of using otoliths for estimating age and growth

Is the timing of spawning in sparid fishes a response to sea temperature regimes?

Published spawning seasons of sparid fish were investigated to determine if there were consistent patterns that could be related to large-scale physical variability, and whether these relationships were species-specific or characteristic of higher taxonomic groupings. For individual species, genera and the family Sparidae as a whole, there was a consistent pattern; spawning at lower latitudes was concentrated close to the month of lowest sea surface temperature, while spawning at higher latitudes was more variable with greater deviations from the month of minimum sea surface temperature. The distribution of sparids may be limited by a lack of tolerance of one or more early life-history stage to high water temperatures, so targeting spawning to the coolest part of the year could be a tactic allowing maximum penetration into warmer waters. Such a link between the physiology of early life-history stages and timing of spawning could have direct consequences for patterns of distributions over a number of taxonomic scales. If there are similar constraints on the reproduction of other species, even minor increases in water temperature due to global warming that may be within the tolerance of adults, may impose constraints on the timing of spawning, with flow-on effects for both species and whole ecosystems