South Africa / Norway Programme of Research Cooperation SANCOOP Theme Environment Migration ecology of fishes for improved fisheries management in South Africa
Dr Paul Cowley Dr Tor Næsje 2001 Exchange visits (SA & Norway) 2002 MOU & Drafted proposals 2003 SA/Norway Programme on Research Cooperation Phase I and Phase II 2014 SANCOOP
Movement patterns and management of important estuarine fishery species Migration ecology of adults for improved management
Problem identification No knowledge of movement behaviour, distribution patterns, population dynamics and migrations Current management regulations ineffective Lack of law enforcement = little compliance to regulations
Methods Acoustic telemetry
Fish with transmitter Data - logging receivers
Mortality 7% 5% 24% 56%
Capacity building Rhodes Univ. Postgrad students Lectures + projects Univ. of Zululand Fieldtrips UCT Fieldtrips Fort Hare Univ. BSc (hons) Lectures, tutorials, fieldtrips
Postgraduate students Year Student Degree 2002 Alusha Hitula BSc Honours 2003-5 Amber-Robyn Childs MSc 2005-7 Bronwyn O Connell MSc 2008-12 Rhett Bennett PhD 2008-13 Amber-Robyn Childs PhD 2012-16 Taryn Murray PhD 2014 Nokuthula Daweti BSc Honours 2014 Mike Dames BSc Honours 2014-15 Rachel Kramer MSc 2015-16 Mike Dames MSc 75% Female
Community Outreach SciFest Work shadowing Angler surveys Angler competitions changed format
25+ publications
50+ conference presentations in 13 countries
Acoustic telemetry research Location of published acoustic telemetry studies 1986 2013 (n = 567)
OTN partner R5-million worth of acoustic receivers. Platform Development Grant R 900 000 Platform Development Grant R 3 000 000 ATAP
>100 listening stations???? Ryan Daly
PHASE 3 (SANCOOP): Migration Ecology Receivers in marine environment Receivers in estuarine environment
Leervis Multi-year large-scale movements N SOUTH AFRICA Eastern Cape Mzimvubu Estuary GweGwe!(!( Port St Johns Western Cape!(!(!(!(!(!(!(!(!(!(!(!(!(!( Mossel Bay!( TAGGED PE Harbour 840 mm FL 02-Aug-12!(!(!(!(!(!(!(!(!( Algoa Bay N = 50 Port Alfred SUMMER WINTER 2012 2013 2014 2015 2016
Dusky kob N Local residency SOUTH AFRICA N = 34 Breede Estuary Fish # 23754 Tagged in mouth on 20/10/16 Caught 394 days later Spent 84% of time at sea (16% in estuary) Visited the Breede Estuary 12 times (ave. stay = 5.9 days) Also visited the Duiwenhoks Estuary twice (< 2 days)
Summary Dependence on estuaries High use areas (home range sizes) Proportion of time spent in estuaries Behavioural differences between estuaries Marine-estuarine connectivity HIGH MORTALITY Behavioural pattern of adults confirmed Differences between species THE CHALLENGE
14 other research organisation Commercially exploited species Data-limited species Long-term monitoring of climate change effects
Thank you
Typical life history Estuarine-dependent species Adults spawn at sea Estuary = nursery area Early juveniles 10-60 mm TL Juveniles 1 3 years
Great Fish Estuary single estuary PHASE 1: 2 species, 1 estuary N SOUTH AFRICA 8 10.3 km Study area GREAT FISH RIVER Subsistence fishery 7 7.6 km 6 5.0 km 3.8 km 5 2.5 km 4 1.8 km = Receivers 3 2 1.0 km 0.4 km 1 N
PHASE 2: Many species, many estuaries N SOUTH AFRICA Location of acoustic receivers Great Fish Study area Gamtoos Swartkops Coega Harbour PE Harbour Sundays Kariega Bushmans Woody Cape Kowie Kromme N 0 30 km INDIAN OCEAN
Proportion of time (mean %) 30 Great Fish 30 Goukou 20 20 10 10 0 30 Sundays 0 30 Kowie 20 20 10 10 0 30 Sundays 0 30 Great Fish 20 20 10 10 0 60 Kariega 0 30 Kariega 45 30 20 15 10 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Distance from mouth (% of estuary length)
Vulnerability to fisheries EXAMPLE Leervis (n = 21) Kowie Estuary 33% mortality rate TAGGED TAG DIED DART TAG RECAPTURE KILLED 300 days No sea trips Transmitter ORI dart tag 15 Jan 2013 11 Nov 2013 14 Feb 2014 31 Mar 2014 03 May 2014 303 mm FL 520 mm FL
TAGGED 303 mm FL Caught FOUR times TAG DEAD 300 days No sea trips 11 Nov 2013 Below legal size! Did not spawn once! DART TAG Recaptured THREE times 14 Feb 2014 520 mm FL Tagged TWICE RECAPTURE 31 Mar 2014 Killed ONCE KILLED Transmitter Dart tag 03 May 2014
Spotted grunter Fidelity to home estuary Some large-scale movements Tagged in the Goukou Estuary Data : Cowley, Lamberth & du Plessis