The objective of the meeting was to conduct an assessment of northern and southern Atlantic sword... more The objective of the meeting was to conduct an assessment of northern and southern Atlantic swordfish, following the request from the Commission contained in the [Rec. 02-02] and [Rec. 03-03] by ICCAT. A review of information used in the assessment was conducted by the Group including the conclusion of the ICCAT 2006 Swordfish Stock Structure Workshop held in March. Projections were carried out using different approaches. The Group also evaluated recovery scenarios for both northern and southern Atlantic swordfish.
Tag-recapture data of Atlantic yellowfin from the ICCAT tagging database was used to estimate and... more Tag-recapture data of Atlantic yellowfin from the ICCAT tagging database was used to estimate and revise preliminary growth parameters using methods that account for individual growth variability. Nominal growth rates suggest that Atlantic yellowfin tuna show a decrease in growth rates at about 50 to 60 cm FL, similar to the patterns seen in the Indian Ocean. Parametric growths models were fitted and evaluated using maximum likelihood methods that models the joint density distribution of release and recapture lengths as a function of age by assuming age at release as random variable. A two stanza growth model with a logistic transition was also investigated but preliminary results are sensitive to input parameters, likely as a result of high variability in the data a limited number of long-term recoveries.
SUMMARY Ageing protocols for albacore tuna were revised and compared to the CAA produce in the la... more SUMMARY Ageing protocols for albacore tuna were revised and compared to the CAA produce in the last assessment of 2009. In prior assessments, an application of the Kimura-Chikuni method was used with quarterly mean size at age estimates and associated expected variance at size by age. These estimates are based on the deterministic growth function adopted in 2009. This document describes the application of the algorithms for ageing the 2011 catch at size matrices and compared to estimates of the 2009. RESUME
Many samples of age-length pairs collected from fishery landings show a peculiar pattern where yo... more Many samples of age-length pairs collected from fishery landings show a peculiar pattern where young animals appear to grow very quickly and then suddenly slow down. In many cases this is primarily a consequence of minimum size limit regulations; fish smaller than the limit are not landed and therefore do not appear in the sample. This presents no special concerns if the goal is merely to determine the average size at age in the landings. However, when the goal is more ambitious, such as determining the average size at age in the catch, one must use a model-based approach to adjust for the effects of the minimum size limits. This paper presents one such approach.
... Assessment 3.0 Stephen C. Turner, Clay. E. Porch, Dennis Heinemann, Gerald P. Scott and Mauri... more ... Assessment 3.0 Stephen C. Turner, Clay. E. Porch, Dennis Heinemann, Gerald P. Scott and Mauricio Ortiz Illustration by Diana Rome Peebles 1998., Courtesy of Florida Fish and Wildlife Conservation Commission Division of Marine Fisheries. ...
ABSTRACT Finfish bycatch by the US Gulf of Mexico shrimp fishery is an important issue in the man... more ABSTRACT Finfish bycatch by the US Gulf of Mexico shrimp fishery is an important issue in the management of fisheries resources given the perceived high bycatch mortality on different exploited fish stock in the region. Data from the Bycatch Characterization Project was used in a simulation modeling approach to determine the effects of shrimp bycatch on stock reproductive dynamics and reduction of potential yields for Spanish mackerel ( Scomberomorus maculatus), king mackerel (S. cavalla), red drum (Sciaenops ocellata), and red snapper ( Lutjanus campechanus) in the US Gulf of Mexico. A simulation model (ByFish) was developed that couples the biological dynamics of the fish stocks, commercial and recreational directed fisheries, and the distribution of shrimp fishing effort in a spatio-temporal matrix.An evaluation of the current protocols to generate bycatch estimates revealed that bycatch data does not conform to the general linear model (GLM) assumptions. Instead a delta lognormal model appears as a better alternative. Annual bycatch estimates differed from the two models, in particular for Spanish and king mackerel, and red snapper.ByFish simulations show that bycatch reduced the spawning potential of the fish stocks, effect that increases with higher levels of exploitation from the directed fisheries. At exploitation levels of overfishing definition (OD) levels, for Spanish mackerel and red snapper potential ratios (SPR) declined 18% and 11%, respectively due to shrimp bycatch compared to SPR levels at F rate of maximum sustainable yields (MSY). In terms of yields for the directed fisheries, MSYs were reduced 40% and 50% for Spanish and king mackerel, respectively, and 51% for red snapper due to bycatch.Under the simulation conditions and with shrimp bycatch, biological reference point (BRP) targets of F0.1 was the most conservative exploitation rate in terms of spawning potential (SPR), while FMAX and F 50%Rmax drove the stocks of Spanish mackerel and red snapper into overfished conditions. The red drum stocks were the least affected of all stocks. The ByFish simulator was also used to evaluate different alternatives for bycatch reduction. Gear selectivity modifications (BRD) were more effective in reducing shrimp bycatch compared to shrimp fishing effort restrictions. Experiments show that only in the case of a BRD design with 50% selectivity reduction was effective to reduce F bycatch rates above the 44% target specified for red snapper. Spatio-temporal analyses of bycatch by species and shrimp effort distribution show that area 3 and 4 (off Texas and Louisiana coast) and seasons 2 and 3 (May--December) were the highest season-area (SA) grids of bycatch. Overall these SA account for more than 75% of total bycatch. Experiments that target these particular areas with BRD implementation and shrimp fishing effort restrictions show reductions of F bycatch of 48% and 54% for Spanish and king mackerel, and 34% for red snapper, respectively. These results show that combined alternatives of bycatch reduction were effective and must be considered in order to minimize losses of shrimp catch associated with implementation of BRD, or fishing effort restrictions.
The Cooperative Tagging Center (CTC) of the National Marine Fisheries Service’s Southeast Fisheri... more The Cooperative Tagging Center (CTC) of the National Marine Fisheries Service’s Southeast Fisheries Science Center operates one of the largest and oldest fish tagging programs of its type in the world. Since 1954, more than 35,000 recreational and commercial fishing constituents have voluntarily participated in the CTC, and this has resulted in tagging more than 245,000 fish of 123 species. Although some tagging activities have been conducted by scientists, most of the tag release and recovery activities were achieved by recreational and commercial fishery constituents. Five large highly migratory species have historically represented the Program’s primary target species, including Atlantic bluefin tuna Thunnus thynnus, blue marlin Makaira nigricans, white marlin Tetrapturus albidus, sailfish Istiophorus platypterus, and broadbill swordfish Xiphias gladius. Tagging equipment and procedures for catching, tagging, and resuscitation of species too large to be brought aboard fishing ves...
This study evaluates the performance of circle and comparable size “J” hooks on Atlantic and Paci... more This study evaluates the performance of circle and comparable size “J” hooks on Atlantic and Pacific sailfish, Istiophorus platypterus, and to a lesser extent on Pacific blue marlin, Makaira nigricans. Terminal gear performances were assessed in terms of fishing success, hook location, and bleeding associated with physical hook damage and trauma. Evaluations of trolling with dead bait took place off Iztapa, Guatemala, during the spring and summer of 1999, and assessment of drifting/kite fishing with live bait took place off south Florida during the summer of 1999. Three hundred and sixty Pacific sailfish were caught in Iztapa, Guatemala, to assess terminal gear performance: 235 sailfish were on circle hooks and 125 were on “J” hooks. Circle hooks used on sailfish had hooking percentages (i.e., fish hooked/fish bite) that were 1.83 times higher compared to “J” hooks. Once the fish were hooked, no difference in catch percentage (i.e., fish caught/fish hooked) between hook types was de...
Indices of abundance of blue marlin for the U.S. pelagic longline fishery in the northwest Atlant... more Indices of abundance of blue marlin for the U.S. pelagic longline fishery in the northwest Atlantic and U.S. Gulf of Mexico are presented for the period 1986-2009. The index of weight (kg) per thousand hooks was estimated from the number of caught marlin reported in logbooks by the commercial, and from mean annual weight estimated by scientific observers aboard longline vessels since 1992 (Pelagic Observer Program). The standardization analysis procedure included the following variables: year, area of fishing, gear characteristics (e.g., main line length, number of hooks, light sticks, etc.), and fishing characteristics (e.g., bait type, target species, and vessel type.). The standardized indexes were estimated using Generalized Linear Mixed Models under a Delta lognormal model approach. Blue marlin CPUE increased from 1986 through 1993, followed by a general decline through year 2002, and then a slight increase through 2009. RÉSUMÉ
The objective of the meeting was to conduct an assessment of northern and southern Atlantic sword... more The objective of the meeting was to conduct an assessment of northern and southern Atlantic swordfish, following the request from the Commission contained in the [Rec. 02-02] and [Rec. 03-03] by ICCAT. A review of information used in the assessment was conducted by the Group including the conclusion of the ICCAT 2006 Swordfish Stock Structure Workshop held in March. Projections were carried out using different approaches. The Group also evaluated recovery scenarios for both northern and southern Atlantic swordfish.
Tag-recapture data of Atlantic yellowfin from the ICCAT tagging database was used to estimate and... more Tag-recapture data of Atlantic yellowfin from the ICCAT tagging database was used to estimate and revise preliminary growth parameters using methods that account for individual growth variability. Nominal growth rates suggest that Atlantic yellowfin tuna show a decrease in growth rates at about 50 to 60 cm FL, similar to the patterns seen in the Indian Ocean. Parametric growths models were fitted and evaluated using maximum likelihood methods that models the joint density distribution of release and recapture lengths as a function of age by assuming age at release as random variable. A two stanza growth model with a logistic transition was also investigated but preliminary results are sensitive to input parameters, likely as a result of high variability in the data a limited number of long-term recoveries.
SUMMARY Ageing protocols for albacore tuna were revised and compared to the CAA produce in the la... more SUMMARY Ageing protocols for albacore tuna were revised and compared to the CAA produce in the last assessment of 2009. In prior assessments, an application of the Kimura-Chikuni method was used with quarterly mean size at age estimates and associated expected variance at size by age. These estimates are based on the deterministic growth function adopted in 2009. This document describes the application of the algorithms for ageing the 2011 catch at size matrices and compared to estimates of the 2009. RESUME
Many samples of age-length pairs collected from fishery landings show a peculiar pattern where yo... more Many samples of age-length pairs collected from fishery landings show a peculiar pattern where young animals appear to grow very quickly and then suddenly slow down. In many cases this is primarily a consequence of minimum size limit regulations; fish smaller than the limit are not landed and therefore do not appear in the sample. This presents no special concerns if the goal is merely to determine the average size at age in the landings. However, when the goal is more ambitious, such as determining the average size at age in the catch, one must use a model-based approach to adjust for the effects of the minimum size limits. This paper presents one such approach.
... Assessment 3.0 Stephen C. Turner, Clay. E. Porch, Dennis Heinemann, Gerald P. Scott and Mauri... more ... Assessment 3.0 Stephen C. Turner, Clay. E. Porch, Dennis Heinemann, Gerald P. Scott and Mauricio Ortiz Illustration by Diana Rome Peebles 1998., Courtesy of Florida Fish and Wildlife Conservation Commission Division of Marine Fisheries. ...
ABSTRACT Finfish bycatch by the US Gulf of Mexico shrimp fishery is an important issue in the man... more ABSTRACT Finfish bycatch by the US Gulf of Mexico shrimp fishery is an important issue in the management of fisheries resources given the perceived high bycatch mortality on different exploited fish stock in the region. Data from the Bycatch Characterization Project was used in a simulation modeling approach to determine the effects of shrimp bycatch on stock reproductive dynamics and reduction of potential yields for Spanish mackerel ( Scomberomorus maculatus), king mackerel (S. cavalla), red drum (Sciaenops ocellata), and red snapper ( Lutjanus campechanus) in the US Gulf of Mexico. A simulation model (ByFish) was developed that couples the biological dynamics of the fish stocks, commercial and recreational directed fisheries, and the distribution of shrimp fishing effort in a spatio-temporal matrix.An evaluation of the current protocols to generate bycatch estimates revealed that bycatch data does not conform to the general linear model (GLM) assumptions. Instead a delta lognormal model appears as a better alternative. Annual bycatch estimates differed from the two models, in particular for Spanish and king mackerel, and red snapper.ByFish simulations show that bycatch reduced the spawning potential of the fish stocks, effect that increases with higher levels of exploitation from the directed fisheries. At exploitation levels of overfishing definition (OD) levels, for Spanish mackerel and red snapper potential ratios (SPR) declined 18% and 11%, respectively due to shrimp bycatch compared to SPR levels at F rate of maximum sustainable yields (MSY). In terms of yields for the directed fisheries, MSYs were reduced 40% and 50% for Spanish and king mackerel, respectively, and 51% for red snapper due to bycatch.Under the simulation conditions and with shrimp bycatch, biological reference point (BRP) targets of F0.1 was the most conservative exploitation rate in terms of spawning potential (SPR), while FMAX and F 50%Rmax drove the stocks of Spanish mackerel and red snapper into overfished conditions. The red drum stocks were the least affected of all stocks. The ByFish simulator was also used to evaluate different alternatives for bycatch reduction. Gear selectivity modifications (BRD) were more effective in reducing shrimp bycatch compared to shrimp fishing effort restrictions. Experiments show that only in the case of a BRD design with 50% selectivity reduction was effective to reduce F bycatch rates above the 44% target specified for red snapper. Spatio-temporal analyses of bycatch by species and shrimp effort distribution show that area 3 and 4 (off Texas and Louisiana coast) and seasons 2 and 3 (May--December) were the highest season-area (SA) grids of bycatch. Overall these SA account for more than 75% of total bycatch. Experiments that target these particular areas with BRD implementation and shrimp fishing effort restrictions show reductions of F bycatch of 48% and 54% for Spanish and king mackerel, and 34% for red snapper, respectively. These results show that combined alternatives of bycatch reduction were effective and must be considered in order to minimize losses of shrimp catch associated with implementation of BRD, or fishing effort restrictions.
The Cooperative Tagging Center (CTC) of the National Marine Fisheries Service’s Southeast Fisheri... more The Cooperative Tagging Center (CTC) of the National Marine Fisheries Service’s Southeast Fisheries Science Center operates one of the largest and oldest fish tagging programs of its type in the world. Since 1954, more than 35,000 recreational and commercial fishing constituents have voluntarily participated in the CTC, and this has resulted in tagging more than 245,000 fish of 123 species. Although some tagging activities have been conducted by scientists, most of the tag release and recovery activities were achieved by recreational and commercial fishery constituents. Five large highly migratory species have historically represented the Program’s primary target species, including Atlantic bluefin tuna Thunnus thynnus, blue marlin Makaira nigricans, white marlin Tetrapturus albidus, sailfish Istiophorus platypterus, and broadbill swordfish Xiphias gladius. Tagging equipment and procedures for catching, tagging, and resuscitation of species too large to be brought aboard fishing ves...
This study evaluates the performance of circle and comparable size “J” hooks on Atlantic and Paci... more This study evaluates the performance of circle and comparable size “J” hooks on Atlantic and Pacific sailfish, Istiophorus platypterus, and to a lesser extent on Pacific blue marlin, Makaira nigricans. Terminal gear performances were assessed in terms of fishing success, hook location, and bleeding associated with physical hook damage and trauma. Evaluations of trolling with dead bait took place off Iztapa, Guatemala, during the spring and summer of 1999, and assessment of drifting/kite fishing with live bait took place off south Florida during the summer of 1999. Three hundred and sixty Pacific sailfish were caught in Iztapa, Guatemala, to assess terminal gear performance: 235 sailfish were on circle hooks and 125 were on “J” hooks. Circle hooks used on sailfish had hooking percentages (i.e., fish hooked/fish bite) that were 1.83 times higher compared to “J” hooks. Once the fish were hooked, no difference in catch percentage (i.e., fish caught/fish hooked) between hook types was de...
Indices of abundance of blue marlin for the U.S. pelagic longline fishery in the northwest Atlant... more Indices of abundance of blue marlin for the U.S. pelagic longline fishery in the northwest Atlantic and U.S. Gulf of Mexico are presented for the period 1986-2009. The index of weight (kg) per thousand hooks was estimated from the number of caught marlin reported in logbooks by the commercial, and from mean annual weight estimated by scientific observers aboard longline vessels since 1992 (Pelagic Observer Program). The standardization analysis procedure included the following variables: year, area of fishing, gear characteristics (e.g., main line length, number of hooks, light sticks, etc.), and fishing characteristics (e.g., bait type, target species, and vessel type.). The standardized indexes were estimated using Generalized Linear Mixed Models under a Delta lognormal model approach. Blue marlin CPUE increased from 1986 through 1993, followed by a general decline through year 2002, and then a slight increase through 2009. RÉSUMÉ
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