An update on the feeding habits of fish in the Mediterranean Sea (2002-2015)

In this study we updated the previous compilation of the feeding habits and trophic levels (TROPHs) of Mediterranean fish. In total, 172 publications were retrieved and analysed. Collected data refer to 146 species, with a TROPH value ranging from 2.00 to 4.54. The analysis of TROPH distribution verified the previously proposed classification of species into functional trophic groups. Overall, information on diet composition exits for 203 fish species out of the >700 fishes from the Mediterranean, a fact clearly showing that feeding habits are understudied despite their importance in ecological applications and fisheries management. More than half (60.6%) of these species are classified as omnivores with preference to animal material, 36.5% are carnivores, 1.9% are omnivores with preference to plants, and two (i.e. Siganus luridus and S. rivulatus) are pure herbivores. Finally, towards the direction of filling in information gaps, recommendations for future research are given

Feeding and ecomorphology of three clupeoids in the N Aegean Sea

The present study examines the feeding habits of anchovy (Engraulis encrasicolus), sardine (Sardina pilchardus) and round sardinella (Sardinella aurita). The results are combined with previously published information on feeding-related morphological features (i.e. mouth area, intestine length and tail area) in order to explore morphological affinities between species and the effect of ecomorphology on their co-existence. These species were mainly zooplanktivorous and no dietary differences were found with sex and season. Anchovy preyed mainly on Crustacea larvae, whereas sardine and round sardinella on Copepoda. In the majority of cases (>90%), the individual fractional trophic level of all species ranged between 3.0 and 3.5, classifying them as omnivores with preference to animals. The feeding-related morphological features differed between anchovy and the two other species, whereas only intestine length differed between sardine and round sardinella. The fact that round sardinella’s diet and morphology show a greater resemblance to those of sardine, further support the hypothesis that is a particulate feeder as sardine. Hence the three species tend to exploit the same food resources differently throughout the year. Thus, they make best use of the environment and its resources, in order to avoid competition and achieve optimum feeding conditions throughout their life cycle

What’s on the (publication fee) menu, who pays the bill and what should be the venue?

We address the cost of access to knowledge and its ethical implications in ‘true’, ‘pseudo’ and ‘hybrid’ OA journals

Age at maturity of Mediterranean marine fishes

In this review we collected data on the age at maturity (tm) and maximum reported age (tmax) for 235 stocks of Mediterranean marine fishes, belonging to 82 species, 37 families, 12 orders and 2 classes (Actinopterygii and Elasmobranchii). Among Actinopterygii (mean tm ± SD = 2.20 ± 1.43 y, n = 215), tm ranged from 0.3 y, for the common goby Pomatoschistus microps, to 12 y, for dusky grouper Epinephelus marginatus, while among Elasmobranchii (mean tm ± SD = 5.94 ± 2.47 y, n = 20), tm ranged between 2.7 y, for brown ray Raja miraletus, and 12 y for picked dogfish Squalus acanthias. Overall, the tmax ranged between 1 y, for transparent goby Aphia minuta, and 70 y, for wreckfish Polyprion americanus. The mean tmax of Actinopterygii (tmax ± SD = 10.14 ± 9.42 y) was lower than that of Elasmobranchii (tmax ± SD = 14.05 ± 8.47 y). The tm exhibited a strong positive linear relation with tmax for both Actinopterygii (logtm = 0.58 ´ logtmax – 0.25, r2 = 0.51, P < 0.001) and Elasmobranchii (logtm = 0.67 ´ logtmax – 0.006, r2 = 0.51, P = 0.007). The mean tm/tmax did not differ significantly with sex within Actinopterygii (ANOVA: F = 0.27, P = 0.60, n = 90; females: mean ± SD = 0.276 ± 0.143; males: mean ± SD = 0.265 ± 0.138) and Elasmobranchii (ANOVA: F = 1.44, P = 0.25, n = 10; females: mean ± SD = 0.499 ± 0.166; males: mean ± SD = 0.418 ± 0.133). Finally, the dimensionless ratio tm/tmax was significantly lower (ANOVA: F = 31.04, P < 0.001) for Actinopterygii (mean ± SD = 0.270 ± 0.135, n = 180) than for Elasmobranchii, (mean ± SD = 0.458 ± 0.152, n = 20), when stocks with combined sexes were excluded from the analysis

Editorial note on weight–length relations of fishes

Weight-length relations of fishes are useful for estimation of biomass from length observations, e.g., in fisheries or conservation research. Here we provide some guidance to authors of such papers, in order to facilitate the publication and review process

Editorial note on reproductive biology of fishes

Fish reproductive biology (onset and duration of spawning, sex ratio, maturity stages, length and age at maturity, and fecundity) is important in fisheries research, stock assessment, and management. In this editorial note, we provide some criteria and recommendations on issues of fish reproductive biology, which may be useful in research planning, data analysis and presentation, as well as in manuscript preparation

A Bayesian population model to estimate changes in the stock size in data poor cases using Mediterranean bogue (Boops boops) and picarel (Spicara smaris) as an example

The paper presents an effort to build a biologically realistic, age structured Bayesian model for the stock assessment of data poor fisheries where only aggregated catch data is available. The model is built using prior information from other areas and ecologically or taxonomically similar species. The modeling approach is tested with data poor fisheries on the Cyclades islands in Greek archipelago. The two most important species in the area are selected: bogue (Boops boops) and picarel (Spicara smaris). Both are hermaphroditic. The only data available is the total catch from 1950 to 2010. Information was gathered about natural mortality, recruitment, growth, body size, fecundity, and sex ratio. There were significant problems in finding reliable prior information and a uniform prior was used for fishing mortality. The models at their present stage are not used to give management advice. The biological characteristics of the species in that area should be further studied. However, the posteriors of biological parameters reflect the best available knowledge on these species and they could be used in future studies or in simpler biomass dynamics models as priors

Razvoj grčkog ribarstva tijekom razdoblja 1928. -1939.

In the present study, Greek fisheries landings were extended back to 1928, for the first time, from data derived by the General Statistical Service of Greece during the 1928-1939 period. In particular, we: (a) present the annual fisheries landings for all species combined, fishing effort for all gear-types combined and species-specific landings during 1928-1939, (b) re-allocate the spatial resolution of landings during 1928-1939 to that during 1964-2007, and (c) compare the landings for different periods during 1928-2007. Results showed that during 1928-1939, landings and effort generally increased. The time series of all species landings exhibited a strong between-year variability, with 23 out of 40 species displaying a significant increasing trend. The analysis of fisheries landings over time (1928-2007) displayed four distinct patterns corresponding to four phases of Greek fisheries development: (1) a gradual increase during 1928-1949 (pre-development phase of fisheries), (2) a steeper increase during 1950-1969 (growth phase), (3) a much steeper linear increase during 1970-1994 (fully tο over-exploited phase) and (4) a declining trend during 1995-2007 (collapse phase). These phases coincided chronologically with significant socio-economic and political events that took place in Greece since 1928.U ovom radu, po prvi put, je iznesen status ulova u grčkom ribarstvu i to u razdoblju od 1928. do 1939. godine prema podacima iz Opće statističke službe u Grčkoj. Konkretno, izneseno je slijedeće: a) predstavljen je godišnji ulov ribarstva za sve vrste zajedno, ribolovni napor za sve vrste alata u kombinaciji i vrste specifičnih ulova tijekom razdoblja 1928.-1939., b) ponovno dodijeljive prostorne rezolucije ulova tijekom 1928.-1939., te tijekom 1964.-2007., i c) uspoređen je ulov za različita razdoblja tijekom 1928.-2007. Rezultati su pokazali da su se tijekom 1928.-1939., ulov i ribolovni napor općenito povećali. Vremenske serije svih vrsta ulova su bile izložene jakim međugodišnjim varijabilnostima, te od 40 vrsta njih 23 su pokazale značajan trend rasta. Analiza ukupnog ulova ribarstva tijekom vremena (1928.-2007.) prikazuje četiri različita uzoraka koji obilježavaju četiri faze razvoja grčkog ribarstva: 1. postupno povećavanje tijekom 1928.-1949. (pred-faza razvoja ribarstva), 2. strmo povećanje tijekom 1950.-1969. (faza rasta), 3. značajan linearni porast tijekom 1970.-1994. (faza potpunog dο prekomjernog ulova) i 4. opadajući trend tijekom 1995.-2007. (kolaps faza). Ove faze se kronološki poklapaju sa značajnim socio-ekonomskim i političkim događanjima koja su se zbivala u Grčkoj od 1928. godine