Las agregaciones de desove de Tylosurus pacificus (Beloniformes: Belonidae) y su pesca en el Parque Nacional Natural Utría (Pacífico colombiano) / Spawning aggregations of Tylosurus pacificus (Beloniformes: Belonidae) and their fishery in Utría Park, Colombian Pacific

ResumenAlgunas especies de peces marinos tienen complejas relaciones con los ecosistemas costeros durante sus periodos reproductivos, tal es el caso del pez aguja Tylosurus pacificus, que conforma agregaciones de desove en playas de grava en el Parque Nacional Natural Utría. Se describe la actividad pesquera y algunos aspectos de la biología reproductiva de T. pacificus y se proponen algunas medidas para mitigar el impacto sobre este evento y los procesos ecológicos asociados. Se realizó un monitoreo pesquero entre abril 2008 y febrero 2009 en el Parque Nacional Natural Utría (PNNU), Pacífico colombiano. Se analizaron los volúmenes de captura, estructura por talla, proporción de sexos y fecundidad (n= 84). La longitud total osciló entre 60.5 cm y 104 cm con una media y desviación estándar de 85.35 ± 9.09 cm. La fecundidad promedio fue 189 685.56 ovocitos por gónada, con una moda de 8 mm de diámetro y un desarrollo gonadal asincrónico. La especie desova en forma colectiva en la playa cuando la marea alcanza el nivel más alto durante la luna llena y nueva, generalmente al anochecer. Pescadores que habitan los pueblos cercanos aprovechan este recurso, durante la agregación reproductiva de la especie. Es importante ampliar el estudio de la reproducción de T. pacificus y los procesos ecológicos asociados a su desove para poder dar un aprovechamiento adecuado y garantizar la sostenibilidad de su pesquería a largo plazo.

Abstract:Some species of marine fish have complex relationships with coastal ecosystems during their reproductive periods, as the needle fish Tylosurus pacificus that forms spawning aggregations in gravel beaches in Utría Park. We described fishery and some aspects of the reproductive biology of T. pacificus and proposed some strategies to mitigate the impact of this event and associated ecological processes. Fisheries monitoring were conducted between April 2008 and February 2009 in the Utría National Park, Colombian Pacific. Catch volumes, length structure, sex ratio and fecundity (n= 84) were analyzed. The total length ranged among 60.5 and 104 cm with a mean and standard deviation of 85.35 ± 9.09 cm. The average fertility of oocytes per gonad was 189 685.56, with a mode of 8 mm diameter and an asynchronous gonadal development. This species spawns collectively on the beach when the tide reaches the highest level during full and new moon, usually in the evening. Fishermen of a near town take advantage of the spawning aggregation of this species. The reproduction study of T. pacificus and ecological processes associated with their spawning, should be expanded to give adequate use, and ensure the sustainability of their fishery over the long term. Rev. Biol. Trop. 65 (1): 77-87. Epub 2017 March 01.

[Spawning aggregations of Tylosurus pacificus (Beloniformes: Belonidae) and their fishery in Utría Park, Colombian Pacific]. / Las agregaciones de desove de Tylosurus pacificus (Beloniformes: Belonidae) y su pesca en el Parque Nacional Natural Utría (Pacífico colombiano).

Some species of marine fish have complex relationships with coastal ecosystems during their reproductive periods, as the needle fish Tylosurus pacificus that forms spawning aggregations in gravel beaches in Utría Park. We described fishery and some aspects of the reproductive biology of T. pacificus and proposed some strategies to mitigate the impact of this event and associated ecological processes. Fisheries monitoring were conducted between April 2008 and February 2009 in the Utría National Park, Colombian Pacific. Catch volumes, length structure, sex ratio and fecundity (n= 84) were analyzed. The total length ranged among 60.5 and 104 cm with a mean and standard deviation of 85.35 ± 9.09 cm. The average fertility of oocytes per gonad was 189 685.56, with a mode of 8 mm diameter and an asynchronous gonadal development. This species spawns collectively on the beach when the tide reaches the highest level during full and new moon, usually in the evening. Fishermen of a near town take advantage of the spawning aggregation of this species. The reproduction study of T. pacificus and ecological processes associated with their spawning, should be expanded to give adequate use, and ensure the sustainability of their fishery over the long term.

Genetic diversity and population structure of Hyporhamphus sajori (Beloniformes: Hemiramphidae) inferred from mtDNA control region and msDNA markers.

This paper presents preliminary data on the genetic diversity and population structure of Hyporhamphus sajori by analysing a 510 bp sequence in the mitochondrial DNA (mtDNA) control region and eight polymorphic microsatellite DNA loci. The H. sajori individuals from different locations were indistinguishable from one another based on mtDNA variation, as demonstrated with a neighbour-joining tree and minimum spanning network analysis. Low level of genetic diversity and the absence of population structure in H. sajori from the north-west Pacific Ocean, combined with negative indices for neutral evolution in these populations, suggest that H. sajori underwent a population expansion after a recent bottleneck. The Structure analysis, discriminant analysis of principal components (DAPC) and the pair-wise ΦST values after Bonferroni correction using eight microsatellite loci provided no clear inference on the genetic differentiation and thus no evidence of population structure of H. sajori. The genetic connectivity among locations might be due to fairly high gene flow via transport of eggs and larvae by the Kuroshio and Tsushima warm current. This study revealed low levels of genetic diversity and suggested high level of contemporary gene flow among populations of H. sajori in the East (Japan) Sea and the Pacific Ocean.

Ballistic Beloniformes attacking through Snell's Window.

Needlefishes (Beloniformes) were observed employing a range of stalking and attacking behaviours to attack schools of bait fishes ranging from the use of tactics common to predatory fishes to a novel behaviour: the use of leaping, aerial attacks. These aerial attacks are suggested to serve two purposes: to extend the attack range of the needlefishes and to reduce their prey's potential for evasion. Furthermore, a third purpose is hypothesized that the needlefishes are taking advantage of Snell's Window, an optical effect which may mask their approach to their prey.

Competition drives sophisticated hunting skills of archerfish in the wild.

Several animals are renowned for their cognitive skills, such as tool use, metacognition or social learning. However, it remains puzzling why some species excel whereas others - sometimes even closely related ones - do not. Archerfish show a remarkable assembly of skills in the context of their unique hunting behavior in which they down aerial prey with shots of water. Hoping to find ecological factors behind these skills, we have over the past years regularly traveled to archerfish mangrove habitats in Thailand (Figure 1A). One of our most consistent findings was the presence of other surface-feeding fish, particularly the similar-sized halfbeak Zenarchopterus buffonis, wherever we spotted groups of archerfish (Figure 1A; Supplemental movie S1). We describe here that Zenarchopterus is superbly equipped with water-wave detectors, rapidly detects the impact of prey even in the dark, is active at all times, is usually more numerous than archerfish and supplements its capabilities with visual skills. Without sophisticated additions to their hunting technique archerfish would thus lose most of their downed prey to halfbeaks. We suggest that the evolution of several skills of archerfish may have thus been influenced not only by intraspecific competition [5] but also by competition with other surface-feeding fish species.

Flyingfish feeding ecology in the eastern Pacific: prey partitioning within a speciose epipelagic community.

To test the hypothesis that prey partitioning contributes to community stability in flyingfish, the gut contents of 359 flyingfish specimens (representing five genera and eight species within Exocoetidae and Hemiramphidae) were collected at 50 dip-net stations during hour-long night-time fishing in oceanic waters of the eastern tropical Pacific Ocean between August and November 2007. Analyses using multidimensional scaling, and analysis of similarity revealed significant dietary differences among species, and similarity percentages tests helped identify the specific prey taxa responsible for these differences. Six species specialized on copepods (58·3-96·9% by number), but targeted different families. Specifically, the barbel flyingfish Exocoetus monocirrhus (n = 205) focused on euchaetids (51·6%), the banded flyingfish Hirundichthys marginatus (n = 24) fed on pontellids (21·8%), while the tropical two-wing flyingfish Exocoetus volitans (n = 11) and the bigwing halfbeak Oxyporhamphus micropterus (n = 34) ingested calanoids (54·6 and 17·0%). In contrast, the whitetip flyingfish Cheilopogon xenopterus (n = 73) and the mirrorwing flyingfish Hirundichthys speculiger (n = 4) had generalized diets comprising similar proportions of amphipod, copepod, mollusc and larval fish prey. Distinct differences in mean fullness, highly digested material, per cent empty guts and mean numbers of prey per gut were also synthesized, and uncovered a pattern of asynchronous feeding. Altogether, these findings provide valuable descriptive data on the diets of an understudied group of epipelagic teleosts, and, by extension, suggest that prey partitioning (taxa and feeding times) may influence flyingfish feeding ecology by reducing interspecific competition.

Enzymatic digestion in stomachless fishes: how a simple gut accommodates both herbivory and carnivory.

The lack of a stomach is not uncommon amongst teleost fishes, yet our understanding of this reductive specialisation is lacking. The absence of a stomach does not restrict trophic preference, resulting in fishes with very similar alimentary morphology capable of digesting differing diets. We examined the digestive biochemistry of four beloniform fishes: two herbivorous halfbeaks (Hemiramphidae) and two carnivorous needlefish (Belonidae) to determine how these fishes digest their respective diets with their simple, short gut. We found that although the halfbeaks showed significantly greater α-amylase activity than that of the needlefish (P < 0.01), trypsin, lipase, aminopeptidase and maltase activity were not substantially different between the two families. We also found that habitat (freshwater vs. marine) appears to play a significant role in digestive capability, as the two freshwater taxa and the two marine taxa were significantly different (ANOSIM; dietary Gobal R = 0.544, P = 0.001, habitat Global R = 0.437, P = 0.001), despite their phyletic and dietary similarities. Our findings offer partial support for the adaptive modulation hypothesis, support the Plug-Flow Reactor model of digestion in herbivorous halfbeaks and also support the compartmental model of digestion but suggest that another model is required to describe stomachless carnivorous needlefish.

Aerodynamic characteristics of flying fish in gliding flight.

The flying fish (family Exocoetidae) is an exceptional marine flying vertebrate, utilizing the advantages of moving in two different media, i.e. swimming in water and flying in air. Despite some physical limitations by moving in both water and air, the flying fish has evolved to have good aerodynamic designs (such as the hypertrophied fins and cylindrical body with a ventrally flattened surface) for proficient gliding flight. Hence, the morphological and behavioral adaptations of flying fish to aerial locomotion have attracted great interest from various fields including biology and aerodynamics. Several aspects of the flight of flying fish have been determined or conjectured from previous field observations and measurements of morphometric parameters. However, the detailed measurement of wing performance associated with its morphometry for identifying the characteristics of flight in flying fish has not been performed yet. Therefore, in the present study, we directly measure the aerodynamic forces and moment on darkedged-wing flying fish (Cypselurus hiraii) models and correlated them with morphological characteristics of wing (fin). The model configurations considered are: (1) both the pectoral and pelvic fins spread out, (2) only the pectoral fins spread with the pelvic fins folded, and (3) both fins folded. The role of the pelvic fins was found to increase the lift force and lift-to-drag ratio, which is confirmed by the jet-like flow structure existing between the pectoral and pelvic fins. With both the pectoral and pelvic fins spread, the longitudinal static stability is also more enhanced than that with the pelvic fins folded. For cases 1 and 2, the lift-to-drag ratio was maximum at attack angles of around 0 deg, where the attack angle is the angle between the longitudinal body axis and the flying direction. The lift coefficient is largest at attack angles around 30∼35 deg, at which the flying fish is observed to emerge from the sea surface. From glide polar, we find that the gliding performance of flying fish is comparable to those of bird wings such as the hawk, petrel and wood duck. However, the induced drag by strong wing-tip vortices is one of the dominant drag components. Finally, we examine ground effect on the aerodynamic forces of the gliding flying fish and find that the flying fish achieves the reduction of drag and increase of lift-to-drag ratio by flying close to the sea surface.

Osteological development of the garfish (Belone belone) larvae.

Garfish, Belone belone (Linnaeus, 1761) is an elongate, slander fish inhabiting the Eastern Atlantic and Mediterranean Sea. These fish from the Belonidae (Actinopterygii) family have important commercial value for Croatian fisheries. Samples for research were collected from experimental hatching in the Novigrad Sea. Preparation techniques included fixation in buffered formalin, trypsin clearing and staining with alcian blue and alizarin red. As little is known of garfish osteology and bone morphology, the main goal of this study was to describe ossification process in garfish fry. At hatching, no skeletal structure is present. Newly-hatched larvae also had no osteological elements. Ossification started at 7 day post-hatching (DPH) [total length (TL) 18 mm] with head bones and vertebral neural arch. Head skeleton continued to develop mostly over the period from 7 to 10 DPH. At 21 DPH (TL 49 mm), ossification process seemed to be finished, but it was not possible to distinguish borders of all bones. The primary interest of our research was to understand the growth dynamics as well as transformation of supporting body elements from cartilage to bone. At the end, developmental characteristics and functional aspects of this formation in different fish species are discussed.

Functional morphology of digestion in the stomachless, piscivorous needlefishes Tylosurus gavialoides and Strongylura leiura ferox (Teleostei: Beloniformes).

Belonidae are unusual in that they are carnivorous but lack a stomach and have a straight, short gut. To develop a functional morphological model for this unusual system the gut contents and alimentary tract morphology of Tylosurus gavialoides and Strongylura leiura ferox were investigated. The posterior orientation of the majority of the pharyngeal teeth supports the swallowing of whole large prey, but not their mastication. Mucogenic cells are abundant in the mucosa lining, particularly the esophagus, and their secretions are likely to protect the gut lining from damage while lubricating passage of the prey. Esophagus, anterior intestine, posterior intestine, and rectum all have highly reticulate mucosae. The anterior three gut sections are distensible to accommodate the passage of prey. However, following ingestion large prey are passed to the highly distensible posterior intestine where they rest head first against the ileorectal valve. Alimentary pH ranges from neutral to weakly acidic. Fish prey is digested head first with the head being largely digested while the remainder of the body is still intact. The nondistensibility of the rectum and the small aperture provided by the ileorectal valve suggest the products of intestinal digestion are either small particulates or fluids that pass into rectum where they are absorbed.

Independent evolution of complex life history adaptations in two families of fishes, live-bearing halfbeaks (zenarchopteridae, beloniformes) and poeciliidae (cyprinodontiformes).

We have previously documented multiple, independent origins of placentas in the fish family Poeciliidae. Here we summarize similar analyses of fishes in the family Zenarchopteridae. This family includes three live-bearing genera. Earlier studies documented the presence of superfetation, or the ability to carry multiple litters of young in different stages of development in the same ovary, in some species in all three genera. There is also one earlier report of matrotrophy, or extensive postfertilization maternal provisioning, in two of these genera. We present detailed life-history data for approximately half of the species in all three genera and combine them with the best available phylogeny to make inferences about the pattern of life-history evolution within this family. Three species of Hemirhamphodon have superfetation but lack matrotrophy. Most species in Nomorhamphus and Dermogenys either lack superfetation and matrotrophy or have both superfetation and matrotrophy. Our phylogenetic analysis shows that matrotrophy may have evolved independently in each genus. In Dermogenys, matrotrophic species produce fewer, larger offspring than nonmatrotrophic species. In Nomorhamphus; matrotrophic species instead produce more and smaller offspring than lecithotrophic species. However, the matrotrophic species in both genera have significantly smaller masses of reproductive tissue relative to their body sizes. All aspects of these results are duplicated in the fish family Poeciliidae. We discuss the possible adaptive significance of matrotrophy in the light of these new results. The two families together present a remarkable opportunity to study the evolution of a complex trait because they contain multiple, independent origins of the trait that often include close relatives that vary in either the presence or absence of the matrotrophy or in the degree to which matrotrophy is developed. These are the raw materials that are required for either an analysis of the adaptive significance of the trait or for studies of the genetic mechanisms that underlie the evolution of the trait.

Oviposition cycle in the oviparous fish Xenopoecilus sarasinorum.

To clarify the reproduction of the oviparous teleost Xenopoecilus sarasinorum, changes in oocyte composition and oviposition cycle were investigated. After release, a batch of spawned eggs hung from the urogenital pore by attaching filaments (36.3+/-0.8 in number, n=31; about 4.3-7.8 mm in length, 5-8 microm in diameter) on the chorion (egg envelope) in the vegetal pole region. Females accommodated a cluster of fertilized eggs in a belly concavity until the embryos hatched. Hatching of embryos took place from 18-19 days after oviposition (25 degrees C). Between 0-2 days following hatching, the attaching filaments disappeared from the urogenital pore. Between 3 and 4 days following hatching, most of the females spawned again. The growth of oocytes proceeded slowly throughout the period when the egg cluster was carried in the belly, and no ovulation occurred during this period. If the current brood was accidentally lost, the day of the next oviposition was sooner. This might imply that carrying embryos in the belly affects endocrine activity, as in viviparous reproduction.

Modifications of the falciform process in the eye of beloniformes (Teleostei: Atherinomorpha): evolution of a curtain-like septum in the eye.

In order to comparatively analyze curtain-like septa in the eyes of visually orientated "close-to-surface-predators" among atherinomorph teleosts, we examined the eyes of 24 atherinomorph species under a binocular microscope with regard to the falciform process and related structures in the vitreous cavity. Additionally, falciform process samples were analyzed by transmission electron microscopy. All the studied representatives of the Cyprinodontiformes and Atheriniformes, and of one of the beloniform suborder, Adrianichthyioidei, possess a "typical" processus falciformis. In the eyes of the representatives of the other beloniform suborder, Belonoidei, however, pigmented structures that originate in the region of the optic disc and protrude into the vitreous cavity were noted. In the Hemiramphidae (halfbeaks) and Exocoetidae (flying fishes) these pigmented structures have a more cone-like shape, whereas in the Belonidae (needlefishes) and Scomberesocidae (sauries) horizontally oriented heavily pigmented curtain-like septa occur that divide the vitreous cavity dorsoventrally. It is suggested that the "typical" processus falciformis represents a plesiomorphic feature within the Atherinomorpha, whereas the pigmented modifications of the falciform process must be seen as a synapomorphic character state of the Belonoidei. The curtain-like septum of the Belonidae and Scomberesocidae might have evolved from the cone-like structures that are found in the Exocoetoidea. The functional significance of the pigmented structures in the eye is as yet not clear, except for the curtain-like septum found in Belonidae. It might play a role in visual orientation near the water surface at Snell's window.