Conservation protocol for endemic species gets underway with 36 escalos-do-Sado

Distinguished Unknown until 2024, the escalos-do-Sado (Squalius caetobrigus) have recently made the headlines following the launch of a partnership agreement between the Faculty of Sciences of the University of Lisbon (Ciências ULisboa) and Zoomarine, which aims to promote the conservation of Portuguese endemic species living in freshwater habitats. The new protocol has begun to take effect, with 36 of these small fish now being cared for at Zoomarine. The group of fish, which belongs to a species which only two years ago was revealed by scientific studies, will now be included in a study and breeding programme aimed at the eventual reintroduction of escalos-do-Sado populations into their natural habitat.

“Morphologically, and simply by looking at individuals in the wild, it is difficult to distinguish the escalo-do-Sado (Squalius caetobrigus) from other species of escalos present at other rivers of the Iberian Peninsula, such as escalo-do-Sul (Squalius pyrenaicus) or the escalo-do-Mira (Squalius torgalensis). However, a more detailed analysis and the use of techniques such as computed tomography reveal that there are morphological characteristics that distinguish the escalo-do-Sado from other species, for example “in terms of the number of scales on the lateral line or the characteristics of the skull and jaw bones”, explains Sofia Mendes, collaborator at the Center for Ecology, Evolution and Environmental Changes (CE3C) and researcher at the Swiss Federal Institute of Aquatic Science and Technology (EAWAG), who is responsible for coordinating the agreement between Ciências ULisboa and Zoomarine.

The species that motivated the protocol between Ciências ULisboa and Zoomarine inhabits the rivers and streams of the Sado river basin. The 36 specimens now living at Zoomarine were collected in Ribeira de Grândola (Grandola river bank). The populations are tiny and vulnerable to the effects of climate change.

The colour of escalos-do-Sado ranges from grey to silver. In their natural habitat, they are usually around 10 centimetres in length, with specimens exceeding 20 centimetres being rare. “There are several unanswered questions, but, like other species of the same genus, it is likely to be omnivorous and breeds annually between March and June,” adds Sofia Mendes.

The agreement that has now been signed aims to combine the biodiversity research currently being carried out by Ciências ULisboa with Zoomarine’s facilities and teams specialising in the conservation of aquatic species. Ciências ULisboa is involved through CE3C, which is responsible for the scientific coordination of this protocol and ensures the identification and capture of breeding birds, as well as undertaking the task of monitoring habitats and preparing for reintroduction into natural habitats.

João Neves, Director of Science and Conservation of the Zoomarine, points out that this protocol is intended to build on the various initiatives that have been undertaken with the aim of preserving riverine biodiversity. As well as being responsible for the first Rehabilitation Center for Marine Species in Portugal, which was released in partnership with the Instituto de Conservação da Natureza e Florestas (ICNF), Zoomarine has a track record of participating in emergency response initiatives involving marine mammals and breeding programmes for endangered species, such as the Rola-de-Socorro or the escalo-do-Arade, among others.

“From an institutional perspective, this reinforces Zoomarine’s position as a scientific and technical facility dedicated to supporting Portuguese biodiversity. “We are talking about an organisation with the necessary facilities, specialist teams and complex life-support systems, capable of combining academic research, assisted reproduction, genetic monitoring and environmental education within an integrated model,” says João Neves.

The Zoomarine representative also highlights the experience gained in the rehabilitation of species in accordance with “the highest welfare standards”. The reception of the 36 escalos-do-Sado will focus on “applied conservation” rather than “an exhibition-based initiative”.

“Naturally, each species has its own specific requirements. “In the case of the Sado estuary, technical adjustments were made regarding environmental parameters, water management and scientific monitoring, always in collaboration with the Ciências ULisboa and within the legal framework of the ICNF,” emphasises João Neves, whilst emphasising the primary objective of conserving the 36 fish species: "to lay solid foundations for population recovery in natural ecosystems, “contributing to the recovery of an endemic species that is particularly vulnerable to climate change and pressure on water resources”. Biodiversity is well worth the effort.