Identification of a non-native <em>Cynoscion</em> species (Perciformes: Sciaenidae) from the Gulf of Cádiz (southwestern Spain) and data on its current status

Abstract

Summary:Cynoscion is a genus of fish in the family Sciaenidae from the Atlantic and Pacific American coasts that is important in recreational and commercial fisheries. Morphological analysis identifies a species inhabiting the Gulf of Cádiz (southern Spain) as the weakfish, Cynoscion regalis, a native of the northwest Atlantic. This finding is also confirmed by molecular identification using 16S and Cox1genes. Based on the examination of a previous manuscript, the assignation of this species to the spotted seatrout, Cynoscion nebulosus, is considered a misidentification. C. regalis has been reported in the area since 2011 and is now considered an established species that is distributed along the Guadalquivir River estuary and is a target of local artisanal fisheries. The pathway of introduction is unknown, but possible mechanisms are considered, of which ballast water seems to be the most plausible. A revision of non-native sciaenids also found in European waters is carried out. The ecological impact of weakfish on the local fish community is still unknown and should be object of future studies.Keywords: biological invasion; marine introduction; weakfish; Cynoscion regalis; Guadalquivir estuary; taxonomy.Identificación de una especie no nativa de Cynoscion (Perciformes: Sciaenidae) en el Golfo de Cádiz (suroeste de España) y datos sobre su estado actual Resumen: Cynoscion es un género de peces de la familia Sciaenidae, de importancia en la pesca deportiva y comercial, que habita las costas americanas del Atlántico y el Pacífico. Una especie que habita en el Golfo de Cádiz (suroeste de España) fue identificada mediante análisis morfológico como corvinata real Cynoscion regalis, nativa del Atlántico Noroeste. La identificación también fue confirmada por análisis molecular, utilizando los genes 16S y Cox1. Basándose en el examen de una publicación anterior, la asignación de esta especie a corvinata pintada Cynoscion nebulosus se considera un error de identificación. Existen registros de C. regalis en esta zona desde 2011 y ahora se considera una especie establecida, distribuida a lo largo del estuario del río Guadalquivir y objeto de la pesca artesanal local. La vía de introducción es desconocida, pero se consideran los posibles mecanismos de introducción, de los cuales el agua de lastre parece ser el más probable. Se realizó una revisión de los esciaénidos no nativos en aguas europeas. Aún se desconoce el impacto ecológico de la corvinata real en la comunidad local de peces, que debe ser objeto de futuros estudios.Palabras clave: invasión biológica; introducción de especies marinas; corvinata real; Cynoscion regalis; estuario del Guadalquivir; taxonomía.

An Update on the Invasion of Weakfish Cynoscion regalis (Bloch & Schneider, 1801) (Actinopterygii: Sciaenidae) into Europe

“…A few Gobiidae and Blenniidae species provide examples of such cases (Table 1), probably because of their crevicolous nature [13] and other biological traits that allow individuals to withstand long transport periods (e.g., larvae with large yolk-sacs). [24] Recently, it was mentioned that the first weakfish captured in Europe occurred in the Schelde estuary (Belgium/The Netherlands) on 24 September 2009 ( Figure 1) [5]. This predates the reported introduction of weakfish into Europe at the Sado (Portugal) [2] and Gulf of Cádiz regions [5] by at least three years.…”

“…[24] Recently, it was mentioned that the first weakfish captured in Europe occurred in the Schelde estuary (Belgium/The Netherlands) on 24 September 2009 ( Figure 1) [5]. This predates the reported introduction of weakfish into Europe at the Sado (Portugal) [2] and Gulf of Cádiz regions [5] by at least three years. However, there is no information suggesting that weakfish established eastwards from the English Channel, where the minimum water temperature falls within critical ranges for this species-weakfish cease feeding and die when the water temperature reaches 7.9 • C and 3.3 • C, respectively [25,26].…”

“…News of weakfish capture in the Guadiana estuary in June 2016 continued to provide new reports [3,4], from both scientists [5][6][7] and anglers [8][9][10][11][12]. An update on the information and hypotheses about the introduction of weakfish into Europe is crucial to avoid the perpetuation of erroneous information, to set new hypotheses, and to propose new management solutions.…”

“…The propagule pressure is enormous in the Schelde estuary because it harbors the third busiest container port in Europe (the Port of Antwerp) [32]. Available information points towards the existence of at least two viable populations in the Iberian Peninsula (SW-Europe), one in the Sado region (estuary and adjacent coast of Portugal) [2] and another in the Gulf of Cádiz region ( Figure 1) [5]. The Sado estuary also has a harbor with intense traffic of transoceanic ships; it is the region with the highest number of non-indigenous marine species in Portugal [33], and the sixth busiest European transshipment port is located ~60 km southwards (the Port of Sines) [32].…”

“…The Sado estuary also has a harbor with intense traffic of transoceanic ships; it is the region with the highest number of non-indigenous marine species in Portugal [33], and the sixth busiest European transshipment port is located ~60 km southwards (the Port of Sines) [32]. The Guadalquivir estuary is located 20 km and 25 km away from two ports with international ship traffic (one US military base, one port/shipyard) ( Figure 1) [5].…”