2 Monitoring of Marine Aquaculture
77
Table 2.8 The “uneaten food index” devised by Borg & Schembri (2001) for the purpose of
quantifying and comparing the amount of dead uneaten feed-fish under the different tuna-pens
Index value Description of amount of uneaten feed-fish present on the seabed
0
No uneaten feed-fish present
1
<1 uneaten feed-fish present per m
2 of seabed
2
>1 uneaten feed-fish present per m
2 of seabed, but the fish do not form a
continuous layer covering the seabed
3
>1 uneaten feed-fish present per m
2 of seabed. Fish form a single, uninterrupted
layer within at least a 1 m
2 area on the seabed.
4
>1 uneaten feed-fish present per m
2 of seabed. Fish form two or more uninterrupted layers on top of each other within at least a 1 m
2 area on the seabed.
Table 2.7 Details of specific attributes to be monitored, sampling stations, and frequency of the
required environmental monitoring programme for aquaculture activities in Malta (source: Malta
Environment & Planning Authority 2001)
Environmental attributes to be
monitored
Number of sampling stations Monitoring frequency
Water column: temperature; salinity; dissolved oxygen; turbidity; chlorophyll a; nitrates;
phosphates; ammonia; faecal
coliforms and total bacteria
A sampling site underneath
each cage; Sampling at
points along a perimeter
around the cage site 25 m
away from the cages;
Monthly, for as long as
the fish are kept in the
cages
At least two sampling points
100 m away from the cage
site (according to the
direction of the prevailing
currents)
Sampling sites in areas that
are of ecological, commercial, tourism, or
recreational interest (this
is to be decided on a siteby-site basis)
Sediments: granulometric properties; and organic carbon and
organic nitrogen content
Several stations within the
cage site
Annually, in the same
month each year
Benthos: species diversity; photographic/video evidence
regarding the state of the
seabed; mapping of benthic
communities; core samples
for faunal, granulometric and
sediment analysis as described
for sediments above; seagrass
morphological parameters
(e.g., shoot and leaf density,
shoot length, etc.) where
applicable
Mapping of all benthic communities within the area
occupied by the cages and
their moorings, together
with collection of samples
at stations as necessary
to establish the species
composition of benthic
communities
Annually
77
Table 2.8 The “uneaten food index” devised by Borg & Schembri (2001) for the purpose of
quantifying and comparing the amount of dead uneaten feed-fish under the different tuna-pens
Index value Description of amount of uneaten feed-fish present on the seabed
0
No uneaten feed-fish present
1
<1 uneaten feed-fish present per m
2 of seabed
2
>1 uneaten feed-fish present per m
2 of seabed, but the fish do not form a
continuous layer covering the seabed
3
>1 uneaten feed-fish present per m
2 of seabed. Fish form a single, uninterrupted
layer within at least a 1 m
2 area on the seabed.
4
>1 uneaten feed-fish present per m
2 of seabed. Fish form two or more uninterrupted layers on top of each other within at least a 1 m
2 area on the seabed.
Table 2.7 Details of specific attributes to be monitored, sampling stations, and frequency of the
required environmental monitoring programme for aquaculture activities in Malta (source: Malta
Environment & Planning Authority 2001)
Environmental attributes to be
monitored
Number of sampling stations Monitoring frequency
Water column: temperature; salinity; dissolved oxygen; turbidity; chlorophyll a; nitrates;
phosphates; ammonia; faecal
coliforms and total bacteria
A sampling site underneath
each cage; Sampling at
points along a perimeter
around the cage site 25 m
away from the cages;
Monthly, for as long as
the fish are kept in the
cages
At least two sampling points
100 m away from the cage
site (according to the
direction of the prevailing
currents)
Sampling sites in areas that
are of ecological, commercial, tourism, or
recreational interest (this
is to be decided on a siteby-site basis)
Sediments: granulometric properties; and organic carbon and
organic nitrogen content
Several stations within the
cage site
Annually, in the same
month each year
Benthos: species diversity; photographic/video evidence
regarding the state of the
seabed; mapping of benthic
communities; core samples
for faunal, granulometric and
sediment analysis as described
for sediments above; seagrass
morphological parameters
(e.g., shoot and leaf density,
shoot length, etc.) where
applicable
Mapping of all benthic communities within the area
occupied by the cages and
their moorings, together
with collection of samples
at stations as necessary
to establish the species
composition of benthic
communities
Annually