Fishers' knowledge and seahorse conservation in Brazil

Abstract

From a conservationist perspective, seahorses are threatened fishes. Concomitantly, from a socioeconomic perspective, they represent a source of income to many fishing communities in developing countries. An integration between these two views requires, among other things, the recognition that seahorse fishers have knowledge and abilities that can assist the implementation of conservation strategies and of management plans for seahorses and their habitats. This paper documents the knowledge held by Brazilian fishers on the biology and ecology of the longsnout seahorse Hippocampus reidi. Its aims were to explore collaborative approaches to seahorse conservation and management in Brazil; to assess fishers' perception of seahorse biology and ecology, in the context evaluating potential management options; to increase fishers' involvement with seahorse conservation in Brazil. Data were obtained through questionnaires and interviews made during field surveys conducted in fishing villages located in the States of Piauí, Ceará, Paraíba, Maranhão, Pernambuco and Pará. We consider the following aspects as positive for the conservation of seahorses and their habitats in Brazil: fishers were willing to dialogue with researchers; although captures and/or trade of brooding seahorses occurred, most interviewees recognized the importance of reproduction to the maintenance of seahorses in the wild (and therefore of their source of income), and expressed concern over population declines; fishers associated the presence of a ventral pouch with reproduction in seahorses (regardless of them knowing which sex bears the pouch), and this may facilitate the construction of collaborative management options designed to eliminate captures of brooding specimens; fishers recognized microhabitats of importance to the maintenance of seahorse wild populations; fishers who kept seahorses in captivity tended to recognize the condtions as poor, and as being a cause of seahorse mortality.

Seahorses in focus: local ecological knowledge of seahorse-watching operators in a tropical estuary

“…(daily intense tidal depth variations in the estuary)2681Yes [2] Occurrence determinant1Determined by the presence of mangrove roots as anchoring points and shelter32100Yes [30] Exposition to water currents2Preferentially inhabit backwater areas protected from strong currents3197Yes [3, 30] Salinity1In the mangrove, are abundant in sites with high salinity levels32100Yes [3, 35] Water transparency1Abundant in high transparency level conditions32100No data Seasonal abundance2Abundant in summer (dry season), scarce in winter (wet season).3197Yes [3] Migration period2Rainy season, in winter (May to September)32100Yes [3] Reason for migration2To avoid low salinity levels caused by the rainy season’s freshwater input. Also are removed out of the mangrove to the sea by floods and currents32100Yes [3] Anchoring points6Mangrove roots32100Yes [30, 33, 44]Trophic ecology Diet7Shrimp larvae32100Yes [3, 37, 38]Fish larvae2578 Feeding behavior4Sucks the prey3197Yes [2, 36] Predators10Crabs and fishes32100Yes [3, 40, 44] Is camouflage related to color shift?2Yes. Is capable of changing its own color3094Yes [24]Reproduction Sexual dimorphism1Brooding pou...…”

“…Also are removed out of the mangrove to the sea by floods and currents32100Yes [3] Anchoring points6Mangrove roots32100Yes [30, 33, 44]Trophic ecology Diet7Shrimp larvae32100Yes [3, 37, 38]Fish larvae2578 Feeding behavior4Sucks the prey3197Yes [2, 36] Predators10Crabs and fishes32100Yes [3, 40, 44] Is camouflage related to color shift?2Yes. Is capable of changing its own color3094Yes [24]Reproduction Sexual dimorphism1Brooding pouch present on males32100Yes [25] Reproductive behavior2Contraction to give birth, releasing neonates as a “dust cloud”.2062.5Yes [45] Brood size3500 to 1000 newborns2991Yes [2] Survival rate3Up to 15 %2991Yes [24] Reproductive period1Throughout the year32100Yes [3, 20, 33]CI = number of informants who quoted a consensual response …”

“…Some life story traits make seahorses vulnerable to human pressures, such as: low mobility, small home range, low population density, a predominantly monogamous behavior, low fertility and a long period of parental care [2]. Although they are not used for human food, seahorses have significant commercial value around the world [3]. These iconic fishes are exploited by extractive activities such as fishing (intentional and incidental) for ornamental trade [4] and for dried trade used in traditional medicine in Asian countries [5–7].…”

“…Such knowledge is particularly important to understand human patterns of resource use for management and long-term sustainability, especially in places where scientific knowledge about local human and ecological processes of the seascape is often unknown [15, 16]. Thus, research on the human use of seahorses can fill in gaps of biological and ecological information on these fishes and is often considered to be necessary to subsidize their management and conservation [2, 3, 13]. …”

The presence of the Patagonian seahorse Hippocampus patagonicus Piacentino & Luzzatto, 2004 (Teleostei: Syngnatidae) in Monte Hermoso, southwestern Buenos Aires province, Argentina

“…In addition, they can present a patchy distribution and occur at low densities, which further complicates their localization in poorly explored areas. In these cases, local knowledge, particularly that of fishermen, can help to detect populations, establish their areas of occurrence, and make conservation inferences (Rosa et al 2005).…”