Matthew W. Johnson

National Oceanic and Atmospheric Administration | NOAA · National Marine Fisheries Service/Southeast Fisheries Science Center

A three-year pilot study, the Deep Coral Reef Monitoring Program (DCRMP), expanded the National Coral Reef Monitoring Program’s (NCRMP) established fishery-independent, diver-based reef fish visual survey to upper mesophotic reefs (>30 to 50 m) in the United States (US) Caribbean for the first time. The new DCRMP sample domain (>30 to 50 m) encompa...

Exploitation impacts and management options for 15 coral reef fish species central to the commercial and recreational fisheries of the southern Florida USA coral reef ecosystem were evaluated using a length-based risk analysis (LBRA) framework. Population abundance-at-length composition data were obtained from several regional federal-state samplin...

National Oceanic and Atmospheric Administration’s Coral Reef Conservation Program supports the National Coral Reef Monitoring Program (NCRMP) in the United States Pacific, Atlantic, Caribbean, and Gulf of Mexico. NCRMP conducts standardized observations of biological, climatic, and socioeconomic indicators across American Samoa, Guam, the Main Hawa...

NCRMP provides large-scale data that can be used in partnership with local jurisdictional monitoring to support coral reef management. This report summarizes data collected by the biological sampling of shallow water coral reefs in the USVI and Puerto Rico in 2019 and highlights the NCRMP mission efforts accomplished by NOAA and the associated part...

The expansion of black mangrove Avicennia germinans into historically smooth cordgrass Spartina alterniflora-dominated marshes with warming temperatures heralds the migration of the marsh-mangrove ecotone northward in the northern Gulf of Mexico. With this shift, A. germinans is expected to outcompete S. alterniflora where it is able to establish,...

Linear decomposition model. Y-axis: dry mass at time t divided by initial dry mass. A. germians: r2 = 0.89; S. alterniflora: r2 = 0.95. (TIF)

Double-exponential decomposition model. Y-axis: dry mass at time t divided by initial dry mass. A. germinans: r2 = 0.90; S. alterniflora: r2 = 0.99. (TIF)

This study extended a “data-limited” length-based stock assessment approach to a risk analysis context. The estimation-simulation method used length frequencies as the principal data in lieu of catch and effort. Key developments were to: (i) incorporate probabilistic mortality and growth dynamics into a numerical cohort model; (ii) employ a precaut...

Here we describe the effects of beach morphological features on loggerhead (Caretta caretta) nesting behavior on the barrier islands of the north-central Gulf of Mexico. Our results show that loggerhead crawl length decreases as beach slope increases, and our data comparing nest crawls (resulting in egg laying) versus false crawls (emergence onto t...

The tropically associated black mangrove (Avicennia germinans) is expanding into salt marshes of the northern Gulf of Mexico (nGOM). This species has colonized temperate systems dominated by smooth cordgrass (Spartina alterniflora) in Texas, Louisiana, Florida and, most recently, Mississippi. To date, little is known about the habitat value of blac...

Red Snapper Lutjanus campechanus is the most economically important reef fish in the Gulf of Mexico, and despite being intensively managed, the stock remains overfished. These fish are susceptible to pressure-related injuries (i.e., barotrauma) during fishing that compromise survival after catch and release. Barotrauma-afflicted fish may not only e...

Implanting internal acoustic tags is often a preferred method for tracking fish; however, this procedure can present issues with respect to surgical incision that affect experimental design. This is particularly the case when testing for the effects of barotrauma, where the incision for an internal tag would inadvertently “vent” the fish, precludin...

The objective of this study was to measure the communities associated with different seagrass species to predict how shifts in seagrass species composition may affect associated fauna. In the northwestern Gulf of Mexico, coverage of the historically dominant shoal grass (Halodule wrightii) is decreasing, while coverage of manatee grass (Syringodium...

Red snapper (Lutjanus campechanus) is the most economically important reef fish species in the Gulf of Mexico. Overfished stocks are recovering but may be hindered to due to barotrauma related post-release mortality. Barotrauma afflicted fish may not only experience immediate surface mortality but also delayed mortality upon returning to depth. Usi...

Red Snapper Lutjanus campechanus are the most economically important reef fish in the Gulf of Mexico and a heavily targeted fishery. When brought to the surface from deep water, this species often suffers pressure‐related injuries collectively known as barotrauma. This trauma results in high discard mortality and has affected recovery of the fisher...

The fish length-otolith length relationship is assumed to be linear in traditional length-at-age back-calculation methods. However, slow-growing fish such as red drum (Sciaenops ocellatus) are typically larger and heavier than fast-growing fish of the same size, thus traditional length-at-age back-calculation methods underestimate previous lengths...

Red snapper (Lutjanus campechanus) is considered an ecologically and economically important reef fish species in the Gulf of Mexico. Populations are highly regulated but have failed to recover as expected and stocks remain low. One possible reason for the slow recovery is that red snapper are susceptible to pressure-related injuries (barotrauma) an...

A primary need in fisheries management is the ability to collect high quality and timely data from participants. Recently, this has become particularly essential as it relates to recreational fisheries, especially reeffish fisheries in the Gulf of Mexico. Because most fishermen in the recreational sector directly consume harvested fish and there ar...

Background/Question/Methods Red snapper (Lutjanus campechanus) is considered ecologically and economically one of the most important reef fish species in the Gulf of Mexico. Populations are heavily managed but have failed to recover as expected and stocks remain at an all time low (97% decline). One possible reason for this is that red snapper ar...

Spotted seatrout (Cynoscion nebulosus), is a nonmigratory game fish common in the Gulf of Mexico that is important in estuarine ecosystems. Population dynamics of spotted seatrout were examined using otolith-based age-and-growth models derived from observed and back-calculated length-at-age values. These data were used to identify sex-based differe...

The vermilion snapper Rhomboplites aurorubens supports a highly managed and important reef fishery and can exhibit regional variations in growth, but little is known about what constitutes the diet of this species in the Gulf of Mexico. We examined age, growth, mortality, and diet composition of vermilion snapper from the recreational fishery in th...

Increases in the frequency and duration of hypoxia and the loss of biogenic reefs are two of the most prominent environmental insults to estuaries. We investigated the interaction between moderate hypoxia and habitat restoration activities on estuarine ecosystems by measuring population growth and somatic growth for newly settled Eastern oysters (C...

Recent efforts to restore oyster reefs have resulted in the creation of many reefs with the explicit objective of benefiting local shellfish and finfish fisheries. We evaluated the community responses of the fish (transient and resident), crab, and shellfish species that colonized or utilized a series of restored high- and low-relief oyster reefs a...

To test the effects of habitat fragmentation per se on the survival and growth of the northern quahog (Mercenaria mercenaria Linné), we stocked juvenile quahogs in 10 seagrass patches (Halodule wrightii Ascherson) ranging in size from 0.5–1,750 m2 for two consecutive months during the summer of 2004. As a control, additional quahogs were stocked in...

We tested the effects of habitat fragmentation on the structure (community composition and biomass) and function (predation rates as assessed by tethering) of circular artificial seagrass units (ASUs) located in an area removed from the influence of immigrants from established seagrass meadows. ASUs varied by size (0.1-10 m 2), perimeter, and perim...

We examined C:N:P ratios of seagrass leaves and epiphytic algae from the eastern shoreline of Grand Bay (Alabama, USA) and the entire shoreline of Big Lagoon (Florida, USA) during the summer of 2001 and March 2003, and used contour plotting of N:P ratios in both locations to examine spatial trends in our data. Results indicated phosphorus limitatio...

We used a mesocosm approach to examine howratch characteristics influenced predation and habitat selection in a tritrophic food web. Our experiments included juvenile red drum (Sciaenops ocellatus; RD), juvenile pinfish (Lagodon rhomboides; PF), and grass shrimp (Palaemonetes sp.; GS), members of a food web common in seagrass meadows of the norther...

The role of habitat fragmentation per se on ecological processes is incompletely understood in marine environments. Previous work in fragmented habitats has concentrated on growth of bivalve species, faunal abundances and predation of tethered crabs. Unlike other studies, in the present study we measured abundances of decapods and fishes and estima...

Relationships between somatic growth (length and weight) and two indirect measures of growth (otolith growth, RNA/DNA ratio) were assessed for red drum (Sciaenops ocellatus) under different feeding rations [0%, 2.5%, 5%, 10%, 15%, and 20% body weight (BW)/day] for 30 days. Representative samples from each ration level were taken in 10-day intervals...