Fish Fry Recruiting Devices(HCMR)

1 – Massive production & Dispersion (R Strategy) 2 – Survival is dependent on random factors

3 – Facing the jungle of predators

The survival probability of an individualto reach adulthood is minimal

(± 2 /106)

Development Strategy of Fish

Life cycle of fish

Benthic– Νectobanthic phase1 - 3 Years

Reproduction

Pelagic Phase1 - 3 months

Adults

EggsLarvae

Establishment

Metalarvae

Young individualsFry

Dispersion

Development

Life Cycle

Numeric Balance

10 1 Adults

10 6 Eggs

10 5 Larvae

10 4 Metalarvae

10 2 Young individuals

10 3 Fry

Population dynamics(Αριθμός ατόμων)

Actual Survival1 pair/ 10 5 - 10 7 ancestors

Reproductive dynamics

Development by weight

10 -1 +1

10 -6 -7

10 -6 -5

10 -5 -4

10 -2 -1

10 -4 -3

Development(Kg)

Multiplier: 10 6 - 10

7

Development of fish (weight) From: 0.1-1 mg it reaches: 0,1-100 kg

Intervention and Regulation Features

Nectobenthic phase- Control of fishing pressure & Protection - Very important role playν:

- Selectivity of fishing gears - Large ability for intervention Sustainable fisheries & protection techniques

Pelagic Phase- Control of zooplankton feeders (95-99% loss in the first 2 months- Very important role play:

- Detection & Size- Minimal ability for intervention (Introduction of metalarvae to the habitat)

Settlement- Control of trophic chain (80 - 90% loss from predation)- Very important role play:

- Recruitment zones and environment- Minimal ability for intervention

Eggs

Prelarvae

Larvae

Metalarvae

Fry

Young ind.

AdultsPreadults

1

103

102

10

105

104

106

Population

Reproduction( Re-introduction

105 - 107 eggs / kg per pair)

0 321 Years

Spatial representation of fish life cycle

0 – Reproduction

Eggs

PrelarvaeMetalarvae

1 – Pelagic dispersion(currents) Young

individuals

Adults

Larvae

2 – Coastalsettlement

Fry

Pre-adults 3 – Nectobenthicsettlement

Depth0 -100m

=> Period of massive dispersion (difficult to intervene)

=> Large number of fish with gregarious behavior       (easy to collect them)

=> Area of controlled fishing activity

Zone of intensive fishing activity

Environmental characteristics of Infant fish

- Main areas of infant/larval development (seeking feed) - Coastal areas: Sandy or muddy depth (plenty of organic material) - Depth areas up to 50 m (photosynthetic activity) - Upwelling areas (nutrient recycling -primary production)

Areas of easy access to trawlers if no protection exist

- Other infant growth areas (foraging & protection)- Posidonia sea grass beds- Coral reefs- Small reefs and rocky areas

Fish fry protection devicesA novel way to utilize the high fish reproduction potential

Development of the food chain(Stabilizing the concentration)

Creation of protection zonesand habitats

(Minimization of predation)

Benthic phase1 - 3 years

Reproduction

Pelagic Phase1-3 months

Adults

EggsLarvae

Settlement

Metalarvae

Young individuals

Fry

Dispersion

Ανάπτυξη

Life cycle

Creation of selected fish concentration zones

(Massive concentration)

Creation of proper equipmentfor fish protection

for safe installation

Protection from fisheries

Development of technologiesfor early life stage(Food, Habitats)

Intervention Period

Recruitment and fry protectionEggs

Larvae

Fry Settlement

Coastal zoneArea of device installation

Adults

Recruitment and fry protectionEggs

Larvae

Fry Settlement

Coastal zoneArea of device installation

Adults

Intervention with the creation of habitats for protection from predators

Various types of artificial reefs

Other types of artificial reefs

Small concrete artificial reefs

The alternative solutionFish Fry Protecting Devices

3 Dimensional labyrinthsAlgal formations Permeable cage nets

Prism protection cages

Tree-like 3-dimensional Escape structures

Testing procedure

Installation

Epifauna growth

Fish attraction

Advantages- Disadvantages

Advantages:- Provision of effective protection against natural predation-    Low installation and maintenance costs-    Possibility of constructing large-scale plants-    Ability to remove the plant-    Equivalent effect compared to more expensive permanent facilities-    They are not fishing gears and do not create conflict to commercial fisheries-    Contribution to the sustainable management of marine biological species richness

Disadvantages:- Require legal actions to protect them from fishing activities (trawlers)-    Require possibly physical protection against unauthorized activity    of towed gears-    Short shelf life compared to fixed permanent installations-    They can’t be applied to all fish. But they are covering the main commercial fish species.